YEXNR-11592; No. of pages: 10; 4C: Experimental Neurology xxx (2013) xxx–xxx

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Experimental Neurology journal homepage: www.elsevier.com/locate/yexnr

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Bernice Sist a,d, Karim Fouad a,b, Ian R. Winship a,c,d,⁎

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Centre for Neuroscience, University of Alberta, Edmonton, Alberta T6G 2R3, Canada Faculty of Rehabilitative Medicine, University of Alberta, Edmonton, Alberta T6G 2R3, Canada c Department of Psychiatry, University of Alberta, Edmonton, Alberta T6G 2R3, Canada d Neurochemical Research Unit, University of Alberta, Edmonton, Alberta T6G 2R3, Canada

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Plasticity beyond peri-infarct cortex: Spinal up regulation of structural plasticity, neurotrophins, and inflammatory cytokines during recovery from cortical stroke

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Stroke induces pathophysiological and adaptive processes in regions proximal and distal to the infarct. Recent studies suggest that plasticity at the level of the spinal cord may contribute to sensorimotor recovery after cortical stroke. Here, we compare the time course of heightened structural plasticity in the spinal cord against the temporal profile of cortical plasticity and spontaneous behavioral recovery. To examine the relation between trophic and inflammatory effectors and spinal structural plasticity, spinal expression of brain derived neurotrophic factor (BDNF), neurotrophin-3 (NT-3), tumor necrosis factor-α (TNF-α), and interleukin-6 (IL-6) was measured. Growth-associated protein 43 (GAP-43), measured at 3, 7, 14, or 28 days after photothrombotic stroke of the forelimb sensorimotor cortex (FL-SMC) to provide an index of periods of heightened structural plasticity, varied as a function of lesion size and time after stroke in the cortical hemispheres and the spinal cord. Notably, GAP-43 levels in the cervical spinal cord were significantly increased after FL-SMC lesion, but the temporal window of elevated structural plasticity was more finite in spinal cord relative to ipsilesional cortical expression (returning to baseline levels by 28 post-stroke). Peak GAP-43 expression in spinal cord occurred during periods of accelerated spontaneous recovery, as measured on the Montoya Staircase reaching task, and returned to baseline as recovery plateaued. Interestingly, spinal GAP-43 levels were significantly correlated with spinal levels of the inflammatory cytokines TNF-α and IL-6 as well as the neurotrophin NT-3, while a transient increase in BDNF levels preceded elevated GAP-43 expression. These data identify a significant but time-limited window of heightened structural plasticity in the spinal cord following stroke that correlates with spontaneous recovery and the spinal expression of inflammatory cytokines and neurotrophic factors. © 2013 Published by Elsevier Inc.

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Article history: Received 25 July 2013 Revised 24 October 2013 Accepted 20 November 2013 Available online xxxx

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Keywords: Ischemia Sensorimotor cortex Plasticity Spinal cord Inflammation Neurotrophins GAP-43 TNF-alpha IL-6 BDNF NT-3

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Introduction

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While the brain damage resulting from ischemic stroke is permanent and irreversible in the infarct core, peri-infarct or penumbral tissue surrounding the infarct exists in a state of disrupted energy and ionic homeostasis but remains structurally intact (Astrup et al., 1981; Danton and Dietrich, 2003; Dirnagl and Iadecola, 1999). Partial recovery of sensorimotor impairments during recovery from stroke has been largely attributed to adaptive changes (plasticity) in surviving neural

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Abbreviations: IC, ipsilesional cortex; CC, contralesional cortex; CSC, cervical spinal cord; LSC, lumbar spinal cord; FL-SMC, forelimb sensorimotor cortex; GAP-43, growth associated protein-43; TNF-α, tumor necrosis factor-alpha; IL-6, interleukin 6; BDNF, brain derived neurotrophic factor; NT-3, neurotrophin-3. ⁎ Corresponding author at: 12-127 Clinical Sciences Building, Edmonton, AB T6G 2R3, Canada. Fax: + 1 780 492 6841. E-mail addresses: [email protected] (B. Sist), [email protected] (K. Fouad), [email protected] (I.R. Winship).

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circuits in this peri-infarct tissue (Barbay et al., 2005; Biernaskie and Corbett, 2001; Castro-Alamancos and Borrel, 1995; Conner et al., 2005; Gharbawie et al., 2005; Winship and Murphy, 2009; Zeiler et al., 2013). Supporting this, dramatic changes in the physiology and structure of peri-infarct brain tissue have been reported during recovery (Murphy and Corbett, 2009; Sist et al., 2012; Winship and Murphy, 2009). Both excitatory and inhibitory neurotransmission are altered for weeks after ischemia, and the induction of long-term potentiation is facilitated in peri-lesional cortex seven days after focal cortical stroke (Butefisch, 2003; Carmichael, 2003, 2012; Dancause, 2005; Manganotti et al., 2007; Que et al., 1999; Schiene et al., 1996). Heightened neuroanatomical remodeling is also observed in both presynaptic (axonal fibers and terminals) and postsynaptic (dendrites and dendritic spines) neuronal structures in peri-infarct cortex in the weeks following stroke (Brown et al., 2007, 2009b; Carmichael et al., 2001; Dancause, 2005; Hsu and Jones, 2006; Li et al., 1998; Stroemer et al., 1995; Y. Ueno et al., 2012). In parallel to these structural and physiological adaptations,

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Please cite this article as: Sist, B., et al., Plasticity beyond peri-infarct cortex: Spinal up regulation of structural plasticity, neurotrophins, and inflammatory cytokines during recovery from cortical stroke, Exp. Neurol. (2013), http://dx.doi.org/10.1016/j.expneurol.2013.11.019

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Methods

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Data was collected from male Sprague Dawley rats (n = 77, 350–400 g). All animal protocols were conducted in accordance with Canadian Council on Animal Care Guidelines and approved by the Animal Care and Use Committee: Health Sciences for the University of Alberta. Briefly, rats received focal ischemic stroke (or sham procedure) in targeted regions of the sensorimotor cortex and recovered for a defined period prior to euthanasia and extraction of the brains and spinal cord. Before and after surgical procedures, animals were housed in pairs on a 12-hour day/night cycle and had access to food and water ad libitum.

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Photothrombotic stroke model

Behavioral analysis

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Permanent unilateral focal ischemic stroke of the forelimb and/or hindlimb sensorimotor cortical representations was induced by

To determine the functional consequences of targeted FL-SMC 200 strokes, a separate cohort of rats were trained on the Montoya Staircase 201

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At their specified recovery endpoint, rats were anesthetized with isoflurane and decapitated. Ipsilesional cortex (IC), contralesional cortex (CC) and the cervical and lumbar enlargements (CSC, LSC) of the spinal cord were dissected and homogenized in 1 ml of ice-cold buffer (1% Igepal CA630, 0.1% SDS, 10% glycerol, 1 × TBS), a protease inhibitor cocktail and EDTA as per kit instructions (Thermo Scientific). The homogenate was centrifuged at 20,000 ×g for 30 min at 4 °C. The supernatant was recovered, diluted 20× and assayed for protein using the bicinchoninic protein assay (BCA) with bovine serum albumin (BSA) as standard. Samples were aliquoted and stored at − 80 °C for future use in enzyme-linked immunosorbent assay (ELISA).

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An ELISA was developed to assay changes in GAP-43 protein expression in the IC, CC, CSC, and LSC after photothrombotic ischemic injury to the forelimb sensorimotor cortex (FL-SMC) as a marker for neuroanatomical plasticity. The samples (20 × dilution) and GAP-43 recombinant protein standards (Abcam) were incubated overnight at 4 °C. The wells were washed 3 times with 1 × PBS and incubated with ELISA diluent blocker (1% BSA) for 2 h at room temperature. Following incubation with the blocker, wells were washed 3 times 1 × PBS and incubated with primary antibody, mouse antiGAP-43 antibody (SIGMA, 1:1000) overnight at 4 °C. Following incubation with primary antibody, wells were washed 3 times 1 × PBS and incubated with secondary antibody, biotinylated donkey antimouse IgG (Santa Cruz, 1:500) for 1 h at room temperature. Following secondary antibody incubation, wells were washed 3 times with 1 × PBS and incubated in a substrate solution (3% H2 O2 and tetramethylbenzidine, TMB; 1:100) for 15 min at room temperature shielded from light. Reaction was stopped using 1.8 N H2SO4 and the optical density of each well was determined using a microplate reader (Molecular Devices SpectraMax M5) at 450 nm. To evaluate the expression of cytokines known to modulate inflammation and neuroplasticity in the cortex and spinal cord, commercially available sandwich ELISA kits were used to detect protein expression of the following cytokines: TNF-α, IL-6, NT-3 (all from R & D systems) and BDNF (Millipore). Samples were run and analyzed according to manufacturer's recommended protocol, and the optical density of each well was determined using the microplate reader (450 nm).

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photothrombosis as previously described (Sulejczak et al., 2007; Watson et al., 1985). Briefly, animals were anesthetized with isoflurane (1–4% in 30% O2 and 70% N2O) and placed in a custom stereotaxic apparatus. Core body temperature was maintained at 37 °C ± 0.5 using a heating pad and feedback regulation system with rectal temperature probe (FHC, Inc.) The skull (up to 6 × 6 mm) above the forelimb sensorimotor cortex (Paxinos and Watson, 2007) was thinned using a dental drill. The photosensitive dye Rose Bengal (Sigma) was injected via the lateral tail vein (10% w/v in saline, 30 mg/kg) and the thinned area of the skull was illuminated with a 532 nm laser (Laser Glow LCS-0532-TOC-00050-05, 50 mW). Custom optics were used to adjust the diameter of the beam to either 3 mm or 6 mm in diameter, thereby inducing a partial or complete lesion of the FL-SMC (Fig. 1). Control groups included naïve and sham-operated animals. Sham animals were subject to the same surgical procedure and Rose Bengal injection without skull irradiation. Following surgery, animals were returned to their home cages and recovered for 3, 7, 14 or 28 days prior to euthanasia (Fig. 1F).

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stroke dramatically alters the expression profiles of pro-inflammatory and neurotrophic molecules in the peri-infarct cortex. Elevated expression of the inflammatory cytokines tumor necrosis factor-alpha (TNF-α), interleukin 1-beta (IL-1β), and interleukin-6 (IL-6) has been reported within 72 h of the initial injury (Berti et al., 2002; Block et al., 2005; Clausen et al., 2008; Lambertsen et al., 2012; Loos et al., 2003; Maddahi et al., 2011; Watters and O'Connor, 2011), and trophic effectors including brain derived neurotrophic factor (BDNF) are up-regulated in peri-infarct cortex in hours and days following ischemic injury (Arai et al., 1996; Béjot et al., 2011; Carmichael et al., 2005; Kokaia et al., 1995; Lindvall et al., 1992; Sulejczak et al., 2007; M. Ueno et al., 2012). Physiological, anatomical, and neurochemical adaptations after stroke contribute to the remapping of lesioned functional representations onto new brain locations. Reorganization of the sensorimotor cortex following focal stroke has been observed in animal models and humans recovering from stroke (Castro-Alamancos and Borrel, 1995; Cicinelli et al., 1997; Frost, 2003; Gharbawie et al., 2005; Liepert et al., 2000), and remapping of damaged regions onto ipsilesional tissue close to the infarct correlates with improved recovery (Dijkhuizen et al., 2001; Fridman, 2004; Hsu and Jones, 2006; Johansen-Berg et al., 2002b; Schaechter, 2006; van Meer et al., 2012; Winship and Murphy, 2008). Stroke-induced changes in the spinal cord may also contribute to functional recovery after stroke (DeVetten et al., 2010; Jayaram et al., 2012; Puig et al., 2010; Thomalla et al., 2004; Wang et al., 2012; Yu et al., 2009). Notably, sprouting of axons originating from the uninjured motor cortex into denervated spinal cord gray matter has been reported in rodent models of stroke (LaPash Daniels et al., 2009; Liu et al., 2007; Reitmeir et al., 2011; M. Ueno et al., 2012), and therapies that improve recovery from stroke have been associated with enhanced axonal sprouting from the uninjured corticospinal tract (CST) (Pagnussat et al., 2012; Ramic et al., 2006; Zhang et al., 2010; Zheng et al., 2013). Moreover, manipulating spinal plasticity drastically alters sensorimotor recovery: Reducing growth inhibiting proteoglycans in the spinal cord via intraspinal injection of Chondroitinase ABC enhances axonal sprouting from the uninjured CST and improves performance on sensorimotor tasks (Starkey et al., 2012). Conversely, interfering with BDNF– TrkB signaling via TrkB small interfering RNA infusion into the contralesional motor cortex reduces axonal sprouting from the uninjured cortex and impairs functional recovery after traumatic brain injury (M. Ueno et al., 2012). Here, to determine the spatiotemporal dynamics of structural plasticity in the spinal cord after cortical stroke, we quantified markers of neurite outgrowth in the cortex and spinal cord during long-term recovery from stroke in sensorimotor cortex. Our data define a time-limited and lesion-size specific window for heightened anatomical plasticity in spinal cord after cortical stroke that correlated with spinal expression levels of TNF-α, IL-6 and NT-3.

Please cite this article as: Sist, B., et al., Plasticity beyond peri-infarct cortex: Spinal up regulation of structural plasticity, neurotrophins, and inflammatory cytokines during recovery from cortical stroke, Exp. Neurol. (2013), http://dx.doi.org/10.1016/j.expneurol.2013.11.019

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One-way ANOVA was used to determine effects of stroke on GAP-43, TNF-α, IL-6, BDNF and NT-3 protein expression levels in IC, CC, CSC, and LSC. Group (recovery end point) differences were determined using Newman–Keuls multiple comparison post-hoc tests. Two-way repeated measures (RM) 2-way ANOVA and post-hoc comparisons with the Bonferroni test were used to determine significant effects of stroke size on reaching performance. Correlations between GAP-43 expression and cytokine protein expression were analyzed using the Pearson r. Statistical analyses were performed in GraphPad Prism 5.0a Macintosh version. Data is presented as mean ± s.e.m.

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Functional consequences of partial or full FL-SMC lesion

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Photothrombotic lesions were located approximately at the border between the forelimb motor and somatosensory cortex, and illumination with either a 3 or 6 mm laser beam diameter was used to generate “partial” or “complete” lesions of the FL-SMC (Figs. 1A–D). Both lesion sizes were associated with impaired reaching performance using the stroke-impaired limb on the Montoya staircase reaching task (Figs. 2A,B). Two-way RM-ANOVA of reaching success using the stroke-impaired limb (Fig. 2A) on the Montoya staircase task showed a significant interaction between lesion size and time post-stroke (F(6, 36) = 5.716, P b 0.001). No effect of lesion or time-post stroke was observed using the unimpaired limb (Fig. 2B), and performance 3 days after FL-SMC lesions was approximately 100% in all groups, suggesting that deficits with the stroke-impaired limb did not result

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GAP-43 levels in cortical hemispheres after focal stroke

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ELISAs were used to quantify changes in GAP-43 expression in tissue homogenate derived from the IC, CC, CSC, and LSC after photothrombotic stroke. GAP-43 is a membrane associated component of growth cones in extending axons and is up-regulated during development and after injury (Jacobson et al., 1986; Stroemer et al., 1995). As such, GAP-43 was selected to provide an index of periods of heightened structural plasticity (reflecting greater neurite outgrowth and branching) at 3, 7, 14 and 28 days post-stroke (Benowitz and Routtenberg, 1997; Bomze et al., 2001; Hoffman, 1989; Leu et al., 2010; Zuber et al., 1989). Consistent with previous reports (Carmichael et al., 2005; Stroemer et al., 1995), GAP-43 protein expression was significantly increased in the IC of animals with partial (ANOVA, F(4, 40) = 21.43, P b 0.0001) and complete FLSMC lesion (F(4, 34) = 17.58, P b 0.0001) (Fig. 3A). Post-hoc comparisons revealed significantly greater levels of GAP-43 in the IC following partial and complete injury to the FL-SMC at 3, 7, 14 and 28 days post-injury (Newman Keuls, all P b 0.01). Analysis of the CC of animals with both partial (F(4, 37) = 26.71, P b 0.0001)

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from motivational factors or a relearning period for the task. Rats with partial and complete FL-SMC injury (P b 0.001) performed significantly worse than baseline at 3, 7, and 14 days post-ischemic injury (Bonferroni post-hoc, P b 0.01 and P b 0.001, respectively). Animals with complete FL-SMC injury, but not partial FL-SMC lesion, continued to perform significantly worse at 28 days post-stroke (P b 0.001). Sham animals did not show any reaching impairment with either limb. Histological analysis of lesion size and location was performed on cryosectioned tissue from rats after completion of behavioral testing (Figs. 2C,D). The medial edge of the infarct for partial FL-SMC extended to 2.0 ± 0.1 mm from the longitudinal fissure, with an average diameter of 2.8 ± 0.2 mm and an average lesion volume of 2.8 ± 0.3 mm3. Complete FL-SMC infarcts extended to 1.2 ± 0.2 mm from the midline with an average diameter of 4.6 ± 0.6 mm and an average lesion volume of 6.6 mm3 ± 0.7. Note that these lesion volumes, measured weeks after ischemic onset after extensive gliosis and tissue shifting has occurred, underestimate lesion volumes during acute and subacute recovery periods (Brott et al., 1989; Browning et al., 1996; Shanina et al., 2005). As shown in Fig. 2D, infarcts measured 1 month after photothrombosis are smaller than lesions induced by the same protocol and region of irradiation measured in tissue extracted 3 days after photothrombosis. A comparison of histology against the stereotaxic atlas (Paxinos and Watson, 2007) suggests that partial FL-SMC lesions disrupted much of the primary forelimb motor cortex and the medial half of the primary somatosensory cortex for the forelimb. Complete FL-SMC lesions disrupted the primary motor and primary somatosensory forelimb cortex and extended into the hindlimb somatosensory cortex.

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Reaching task (Montoya et al., 1991) prior to photothrombosis (1D,E). These rats (n = 15) were trained to retrieve chocolate flavored sugar pellets (45 g, Research Diets Inc.) from the steps of the Montoya Staircase apparatus for 2 weeks (twice daily, 15 min per session) prior to photothrombosis. Baseline performance was determined by taking the average of the last 5 sessions, with a minimum criterion for inclusion set at successful retrieval of 9 pellets. Testing consisted of one 15-minute session on 3, 7, 14 and 28 days post-injury. Both stroke-impaired (contralateral) and unimpaired (ipsilateral) limbs were tested. The total number of pellets retrieved in each testing session was counted and is illustrated as percent of baseline performance. After completion of behavioral testing, rats were euthanized as described above. Brains were extracted, flash frozen in − 80 °C isopentane, sectioned at 40 μm thickness on a cryostat (Leica CM3050S). Sections were stained with cresyl violet for histological analysis including determination of infarct volume (estimated using Cavalieri's Principle), diameter, and location. Microphotographs were acquired via light microscopy (Leica DMI 6000B) and images were analyzed using ImageJ for Mac OS X.

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Fig. 1. (A–C) Laser speckle contrast imaging (performed as described in Armitage et al. 2010) showing the pattern of blood flow before and after photothrombotic stroke of the forelimb sensorimotor cortex. Dark vessels represent surface arteries and veins carrying blood, and photothrombosis permanently occludes all surface vasculature (B,C). (D) Schematic illustrating the approximate location of sensorimotor representation of the forelimb (S1FL/M1FL) and hindlimb (S1HL/M1HL) cortex as defined by stereotaxic coordinates (Paxinos and Watson, 2007), and the diameter of laser irradiation used to induce photothrombotic stroke. (E) Experimental timeline of behavioral analyses of functional recovery on the Montoya staircase task to evaluate reaching and fine motor control (n = 15). (F) Timeline of tissue collection to be used for protein analysis for GAP-43, TNF-α, IL-6, BDNF, and NT-3 using enzyme-linked immunosorbent assay (ELISA, n = 62).

Please cite this article as: Sist, B., et al., Plasticity beyond peri-infarct cortex: Spinal up regulation of structural plasticity, neurotrophins, and inflammatory cytokines during recovery from cortical stroke, Exp. Neurol. (2013), http://dx.doi.org/10.1016/j.expneurol.2013.11.019

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Fig. 2. (A,B) Baseline performance on the Montoya staircase task to evaluate skilled forelimb reaching in the stroke-impaired (A) and unimpaired (B) limb on days 3, 7, 14 and 28 postischemic injury. Animals with a partial FL-SMC injury showed a significant deficit in their performance with the stroke affected limb on the Montoya Staircase reaching task only on days 3, 7, and 14 post-ischemic injury, #P b 0.05, ##P b 0.01. Animals with a complete FL-SMC showed significant deficit in their performance on the reaching task as compared to sham operated animals (control) at all time points, ***P b 0.0001. Limbs ipsilateral to the stroke (B) were not impaired in this task after stroke. Data illustrated as mean ± s.e.m. Overall significance was evaluated using RM 2-way ANOVA with Bonferroni post-hoc tests to evaluate significance between lesion size and control values. (C) Schematic representation of lesion size (measured 1 month after stroke) in coronal sections showing photothrombotic infarct resulting from partial and complete FL-SMC injury. (D) Representative images showing lesion size in cryosectioned tissue extracted 3 days or 1 month after photothrombotic stroke. Glial fibrillary acid protein (GFAP) immunohistochemistry was used to highlight the glial scar around the infarct. Note that the infarct volume is larger 3 days after injury than 1 month post-stroke, despite identical initial protocols for photothrombosis and irradiation conditions.

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GAP-43 levels in spinal cord after focal cortical stroke

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GAP-43 protein expression was evaluated in tissue homogenate derived from the CSC and the LSC following partial or complete FL-SMC photothrombotic lesion (Fig. 4). GAP-43 protein expression was significantly increased in the CSC following both partial (ANOVA, F(4, 35) = 4.97, P b 0.01) and complete (F(4, 32) = 17.81, P b 0.0001) FL-SMC infarction (Fig. 4A). Post-hoc comparisons showed that GAP-43 protein expression was greater than control tissue at 7 days post injury (P b 0.01) following partial FL-SMC and at 7 (P b 0.0001) and 14 days (P b 0.001) post-injury following complete FL-SMC. Partial FL-SMC did not alter GAP-43 levels in the LSC (F(4, 39) = 2.03, ns). Conversely, complete FL-SMC injury induced a significant increase in GAP-43 protein expression in the LSC (F(4, 34) = 16.44, P b 0.0001) (Fig. 4B), and post-hoc comparisons showed a significant increase in GAP-43 at days 3 (P b 0.05), 7 and 14 (P b 0.0001) post-injury. These GAP-43 measures suggest

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and complete FL-SMC injury (F(4, 33) = 10.98, P b 0.0001) also revealed significant increases in GAP-43 protein expression after stroke (Fig. 3B). Post-hoc comparisons showed significantly greater GAP-43 protein expression at all time points as compared to control levels following partial FL-SMC injury (P b 0.0001) and at 7 days (P b 0.0001) and 14 days (P b 0.001) following complete FL-SMC lesion. As such, our analysis of GAP-43 protein expression confirms that both partial and complete FL-SMC lesions are associated with heightened structural plasticity in cortex ipsilateral and contralateral to the infarct.

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a time-limited increase in structural plasticity in CSC during the first two weeks after photothrombosis, with the amount and spatial extent of elevated GAP-43 protein expression varying as a function injury severity.

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Inflammatory cytokine expression profiles in CSC after FL-SMC stroke

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To examine if periods of heightened anatomical plasticity in the spinal cord were associated with local expression of inflammatory cytokines, and thereby identify potential mechanisms for heightened neuroanatomical remodeling, ELISAs were used to evaluate TNF-α and IL-6 levels in CSC-derived tissue homogenate from rats after complete FL-SMC lesion. TNF-α and IL-6 protein levels in the CSC were both altered by complete FL-SMC injury (ANOVA, TNF-α, F(4, 24) = 5.007, P b 0.01; IL-6, F(4, 26) = 3.153, P b 0.05) (Figs. 5A,B). Post-hoc comparisons revealed that both TNF-α and IL-6 protein levels peaked 14 days post-injury (P b 0.01 and P b 0.05, respectively), a peak in expression that coincides with maximal GAP-43 levels in the same tissue. Correlation analysis confirmed that the protein expression profile of GAP-43 was highly correlated with levels of TNF-α (r2 = 0.9718, P b 0.01) and IL-6 (r2 = 0.9726, P b 0.01) (Figs. 6A,B).

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BDNF and NT-3 protein expression profiles in CSC after FL-SMC stroke

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The neurotrophic factors NT-3 and BDNF are up-regulated following 340 injury and promote neuronal survival and sprouting of axons after 341 spinal cord injury (Bradbury et al., 1999; Bregman et al., 1997; Di 342

Please cite this article as: Sist, B., et al., Plasticity beyond peri-infarct cortex: Spinal up regulation of structural plasticity, neurotrophins, and inflammatory cytokines during recovery from cortical stroke, Exp. Neurol. (2013), http://dx.doi.org/10.1016/j.expneurol.2013.11.019

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Fig. 3. Time course of GAP-43 protein levels in cortex after partial and complete injury to the FL-SMC. ELISA was developed to measure changes in protein expression at 3, 7, 14 and 28 days post-photothrombotic stroke in the ipsilesional cortex (A) and contralesional cortex (B). Data are expressed as mean ± s.e.m. Newman Keuls post hoc tests used to determine significance within groups, **P b 0.01, ***P b 0.0001.

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In this study, GAP-43 protein expression was used as an index of periods of heightened structural plasticity. As an integral component of the growth cone, GAP-43 expression is correlated with heightened neurite outgrowth and is essential for axonal extension (Benowitz and Perrone-Bizzozero, 2006; Dent and Meiri, 1992; Frey et al., 2000; He et al., 1997; Liepert et al., 1998, 2000; Ng et al., 1988; Skene, 1989). As such, our data provide evidence of a time-limited period of heightened structural remodeling in the cortex and spinal cord after focal cortical stroke. Consistent with previous studies (Carmichael et al., 2005; Stroemer et al., 1995), GAP-43 expression was elevated in the IC, peaking two weeks after FL-SMC lesion, and remained elevated one month after

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Giovanni et al., 2003; Grill et al., 1997; Hammond et al., 1999; Hayashi et al., 2000; Schnell et al., 1994; Song et al., 2001; Vavrek et al., 2006; Ye and Houle, 1997). To evaluate if these neurotrophic factors are up-regulated locally during enhanced structural plasticity in the spinal cord after cortical stroke, levels of BDNF and NT-3 were evaluated in tissue homogenate from the CSC following complete ischemic injury to the FL-SMC. FL-SMC stroke significantly changed BDNF levels in the CSC (F(4, 27) = 14.58, P b 0.0001) (Fig. 5C). Posthoc analysis showed a significant, transient increase in BDNF protein expression at 3 days post-injury (P b 0.0001). No main effect of FL-SMC was observed for NT-3 protein expression levels (F(4, 23) = 1.99, P = 0.13, n.s.) (Fig. 5D). However, the protein expression profile for NT-3 was highly correlated with GAP-43 protein expression (r2 = 0.96, P b 0.01). No correlation was observed between protein expression profiles of GAP-43 and BDNF (r2 = 0.02369) (Figs. 6C,D).

Fig. 4. Time course of GAP-43 protein levels in spinal cord after partial and complete injury to the FL-SMC. ELISA was developed to measure changes in protein expression at 3, 7, 14 and 28 days post-photothrombotic stroke in cervical (A) and lumbar (B) enlargement of the spinal cord. Data are expressed as mean ± s.e.m. Newman Keuls post hoc tests used to determine significance within groups, **P b 0.01, ***P b 0.0001.

injury. The heightened axonal plasticity suggested by these findings correlates temporally with elevated rates of formation of postsynaptic dendritic spines in peri-infarct tissue (Brown and Murphy, 2007; Brown et al., 2007, 2009a), indicative of a post-stroke period of anatomical adaptation that facilitates rewiring of disrupted connections. A transition from elevated GAP-43 (axonal sprouting) toward increased synaptogenesis (indicated by synaptophysin expression) has been reported in the peri-infarct cortex during the weeks following stroke (Carmichael et al., 2005; Madinier et al., 2013; Stroemer et al., 1995). The functional importance of this remodeling is supported by studies in individuals with stroke and from animal models that show that peri-infarct functional reorganization correlates with improved recovery from stroke-induced disability (Dijkhuizen et al., 2001; Hsu and Jones, 2006; van Meer et al., 2012; Winship and Murphy, 2008). Increased structural remodeling was not restricted to IC, as heightened GAP-43 protein expression was observed in the CC and in the spinal cord. The importance and extent of functional reorganization in cortex contralateral to an ischemic injury remain controversial (Johnston et al., 2012; Takatsuru et al., 2009). Clinical data suggest that reorganized activation in novel ipsilesional sensorimotor areas has been correlated with improved recovery after stroke (Calautti et al., 2010; Fridman, 2004; Johansen-Berg et al., 2002a). Contrasting this, contralesional activation is associated with severe ipsilesional brain damage and therefore with poor recovery (Fujii and Nakada, 2003; Johansen-Berg et al., 2002b). Surprisingly, in our experiments GAP-43 levels in CC were higher after partial FL-SMC lesion than after complete lesion, an apparent contradiction with findings showing contralesional reorganization after larger strokes. However, even in

Please cite this article as: Sist, B., et al., Plasticity beyond peri-infarct cortex: Spinal up regulation of structural plasticity, neurotrophins, and inflammatory cytokines during recovery from cortical stroke, Exp. Neurol. (2013), http://dx.doi.org/10.1016/j.expneurol.2013.11.019

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our complete FL-SMC lesions, the majority of the IC remains uninjured. As such, we would expect ipsilesional remapping to drive recovery even in the complete lesions and would not anticipate significant contralesional remapping (as reported in studies of severe ipsilesional infarction). Thus, the functional consequences of structural plasticity in the contralesional cortex after such moderate injuries remain to be determined. FL-SMC lesions increased GAP-43 protein levels in the spinal cord in a time-limited and with lesion-size dependent manner. After partial lesion of the FL-SMC, increases in GAP-43 protein expression peaked one week after injury and were restricted to the CSC. After a complete lesion of the FL-SMC (with infarction extending into the hindlimb SMC), increases in GAP-43 protein expression in the CSC were more pronounced and peaked two weeks after injury. Moreover, infarction of the hindlimb SMC was reflected by an increase in GAP-43 expression in the LSC. For both partial and complete FL-SMC lesions, stroke induced increases in GAP-43 in the spinal cord were time-limited and returned to baseline by four weeks after stroke. Notably, peak GAP-43 expression in CSC 7 and 14 days after FL-SMC lesion occurs during periods of spontaneous recovery of forelimb function (as indicated by improvements in Montoya Staircase performance between 3 and 14 days post-stroke) and returns to baseline as recovery plateaus. Based on data showing sprouting of axon collaterals from uninjured CST into strokedenervated gray matter in the spinal cord (DeVetten et al., 2010; Jayaram et al., 2012; LaPash Daniels et al., 2009; Liu et al., 2007, 2008, 2009, 2012; Omoto et al., 2011; Puig et al., 2010; Reitmeir et al., 2011; Starkey et al., 2012; Thomalla et al., 2004; Wang et al., 2012; Yu et al., 2009; Zhang et al., 2010), we postulate that the increases in spinal cord levels of GAP-43 after FL-SMC would primarily

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Fig. 5. Inflammatory and trophic factor expression in spinal cord after complete FL-SMC. TNF-α protein expression is significantly increased at 3 days post-injury and remains elevated at 14 days before returning to control levels at 28 days post-injury (A). IL-6 protein expression is transiently and significantly increased at 14 days post-injury before returning to control levels at 28 days following a larger lesion (B). BDNF protein expression showed a transient increase following a complete lesion to the FL-SMC. Peak BDNF protein expression occurred at 3 days post-injury before returning toward control levels at 7 days post-stroke (C). NT-3 protein expression showed no statistically significant differences in protein expression however there was a trend toward increased protein expression by 14 days post-stroke (D). One-way ANOVA was used to calculate overall effect and Newman–Keuls post-hoc tests were used to compare each time point to control levels, *P b 0.05, **P b 0.01, ***P b 0.001. Data are expressed as mean ± s.e.m.

reflect sprouting of descending axons from the CST into denervated spinal gray matter. However, given that axonal rewiring likely includes ipsilateral (CST fibers originating in uninjured motor cortex sprouting into stroke affected gray matter) and contralateral (sprouting of spared axons originating in peri-infarct cortex) components, our measures of spinal plasticity provide a summation of structural plasticity at the level of the cervical or lumbar cord incorporating sprouting from CST originating in both cortical hemispheres, as well as neurite outgrowth from interneurons in the spinal cord (as has been reported after spinal cord injury (Bareyre et al., 2004; Vavrek et al., 2006)). Our data therefore suggests that this summed CST plasticity is time-limited, occurring primarily in the first two weeks after injury, and more pronounced with more severe cortical injury.

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Interestingly, our data show expression of GAP-43 in the CSC is highly correlated with the expression profiles of the pro-inflammatory cytokines TNF-α and IL-6. Increased expression of inflammatory molecules such as TNF-α and IL-6 during the acute and sub-acute postinjury periods and their role in the evolution of the injury core and contributions to secondary damage following stroke and spinal cord injury have been described in detail (e.g. Clausen et al., 2008; Dirnagl and Iadecola, 1999; Hayashi et al., 2000; Hill et al., 1999; Lambertsen et al., 2012; Stammers et al., 2011; Uno et al., 1997; Wang et al., 2007). However, while increases in inflammatory cytokines occur during acute and subacute post-injury periods, progressive Wallerian degeneration in the CST persists for months after cortical stroke (Benowitz and Routtenberg,

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lesioning the forelimb motor cortex (Weishaupt et al., 2010). Secondary damage in both the cervical and thoracic spinal cord was apparent one month after injury but was not associated with persistent microglial activation (Weishaupt et al., 2010). Thus, the increases in the expression of the inflammatory cytokines TNF-α and IL-6 reported here therefore parallel the temporal profile of microglial activation in the cord following cortical injury and suggest a role for TNF-α and IL-6 initiating secondary damage. Our analysis of inflammatory effectors is focused on TNF-α and IL-6 because they are well-characterized inflammatory cytokines that also have established roles in regulating protective, synaptic, and regenerative processes (Hakkoum et al., 2007; Marchetti, 2004; Oshima et al., 2009; Suzuki et al., 2008; Turrin, 2006; Yang et al., 2012). A number of studies suggest that under normal physiological and pathophysiological conditions TNF-α contributes to regulation of synaptic function and plasticity (O'Connor, 2013). Acute application of TNFα induces a rapid and persistent decrease of inhibitory synaptic strength and potentiation of glutamatergic transmission via the down regulation of cell-surface levels of GABAA receptors and an increase in the number of postsynaptic AMPA receptors, respectively (Pribiag and Stellwagen, 2013). TNF-α has also been reported to control glutamate release from astrocytes and thereby regulate astrocyte-dependent synaptic modulation (Santello et al., 2011). A direct role for TNF-α in neuroanatomical plasticity after injury is suggested by in vitro studies (Saleh et al., 2011) and in vivo investigations of TNF-α deficient transgenic mice. Notably, these mice have no developmental differences in CST anatomy but do not exhibit increased axonal sprouting of the uninjured CST in the cervical spinal cord after cortical contusion injury (Oshima et al., 2009). Moreover, TNF-α deficient mice show no improvement in locomotor function, and remain impaired relative to wild types at 14, 21, and 28 days after injury (Oshima et al., 2009). Similarly, IL-6 mediates inflammation but has also been associated with synaptic plasticity and neurite outgrowth (Hakkoum et al., 2007; Parish et al., 2002; Suzuki et al., 2008). A role in synaptic plasticity is suggested by studies of IL-6 knockout mice that exhibit enhanced dendritic excitatory postsynaptic potentials and somatic population spikes in hippocampal slices, as well as studies that suggest a role for IL-6 in regulating the kinetics of LTP (Nelson et al., 2012). Notably, IL-6 also up regulates GAP-43 expression and axonal sprouting in neuronal cultures, and intrathecal delivery of IL-6 after spinal injury enhances synapse formation and promotes locomotor recovery (Yang et al., 2012). Here, we show that IL-6 and TNF-α are up regulated locally in the spinal cord after cortical stroke. IL-6 and TNF-α protein expression levels correlated with GAP-43 levels in the same tissue, supporting evidence that spinal TNF-α and IL-6 can up-regulate axonal sprouting in the spinal cord and contribute to spontaneous recovery after brain injury.

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BDNF is a neurotrophic factor expressed throughout the CNS (Ernfors et al., 1990; Hohn et al., 1990; Rocamora et al., 1992), and BDNF signaling through the TrkB receptors regulates neuroprotective processes and activity dependent synaptic plasticity (Larsson et al., 1999; Nagappan and Lu, 2005; Sulejczak et al., 2007; Vavrek et al., 2006; Yoshii and Constantine-Paton, 2010). Following stroke and spinal cord injury, a transient but robust increase in BDNF mRNA and protein expression in neurons and non-neuronal cells is observed (Arai et al., 1996; Béjot et al., 2011; Hayashi et al., 2000; Kokaia et al., 1995; Madinier et al., 2013) and is a critical contributor to functional recovery (Ploughman et al., 2009; Vavrek et al., 2006; Weishaupt et al., 2013) and structural plasticity (Horch and Katz, 2002; Kokaia et al., 1995). Notably, disruption of BDNF production after stroke prevents rehabilitation induced recovery in rats (Ploughman et al., 2009). Similarly, the recovery of limb function elicited by delayed activation of AMPA receptors during stroke recovery is mediated by release of BDNF in peri-infarct cortex,

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Fig. 6. Correlation between GAP-43 levels and TNF-α (A), IL-6 (B) and NT-3 (C), and BDNF (D) levels in CSC after complete FL-SMC lesion. TNF-α, IL-6 and NT-3 protein levels were highly correlated with GAP-43 protein expression. Correlations calculated using Pearson r.

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1997; Bomze et al., 2001; DeVetten et al., 2010; Hoffman, 1989; Iizuka et al., 2005; Jacobson et al., 1986; Kataoka et al., 1989; Lama et al., 2011; Leu et al., 2010; Puig et al., 2010; Thomalla et al., 2004; Zuber et al., 1989). Interestingly, delayed microglial activation has been observed in the CSC of rats one week after cortical ischemic injury

Please cite this article as: Sist, B., et al., Plasticity beyond peri-infarct cortex: Spinal up regulation of structural plasticity, neurotrophins, and inflammatory cytokines during recovery from cortical stroke, Exp. Neurol. (2013), http://dx.doi.org/10.1016/j.expneurol.2013.11.019

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Previous studies suggest that anatomical remodeling occurs at the level of the spinal cord after brain injury and contributes to recovery. These data illustrate the spatiotemporal dynamics of heightened structural plasticity in the spinal cord, define the effect of lesion-size on spinal plasticity, and identify a limited temporal window for anatomical remodeling in the cord. The abrupt closure of this window, and its temporal correlation with periods of functional recovery, suggest that reopening this window may facilitate greater recovery after stroke. Moreover, our data suggest a role for IL-6, TNF-α, and NT-3 in regulating spinal plasticity, and provide further support for BNDF as a critical factor in initiating remodeling.

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This work was supported by the Heart and Stroke Foundation of Canada (Grant-in-Aid, IRW), the Alberta Innovates Health Solutions (Scholarship Award, IRW), the Natural Sciences and Engineering Research Council of Canada (Discovery Grant, IRW), and the Centre for Neuroscience (BS).

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References

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Alto, L.T., Havton, L.A., Conner, J.M., Hollis II, E.R., Blesch, A., Tuszynski, M.H., 2009. Chemotropic guidance facilitates axonal regeneration and synapse formation after spinal cord injury. Nat. Publ. Group 12, 1106–1113. Arai, S., Kinouchi, H., Akabane, A., Owada, Y., Kamii, H., Kawase, M., Yoshimoto, T., 1996. Induction of brain-derived neurotrophic factor (BDNF) and the receptor trk B mRNA following middle cerebral artery occlusion in rat. Neurosci. Lett. 211, 57–60. Armitage, G.A., Todd, K.G., Shuaib, A., Winship, I.R., 2010. Laser speckle contrast imaging of collateral blood flow during acute ischemic stroke. J. Cereb. Blood Flow Metab. 30, 1432–1436. Astrup, J., Siesjö, B.K., Symon, L., 1981. Thresholds in Cerebral Ischemia — the Ischemic Penumbra. Barbay, S., Plautz, E.J., Friel, K.M., Frost, S.B., Dancause, N., Stowe, A.M., Nudo, R.J., 2005. Behavioral and neurophysiological effects of delayed training following a small ischemic infarct in primary motor cortex of squirrel monkeys. Exp. Brain Res. 169, 106–116. Bareyre, F.M., Kerschensteiner, M., Raineteau, O., Mettenleiter, T.C., Weinmann, O., Schwab, M.E., 2004. The injured spinal cord spontaneously forms a new intraspinal circuit in adult rats. Nat. Neurosci. 7, 269–277.

U

N

C

O

561

564 565

D

539 540

T

537 538

C

535 536

E

533 534

R

531 532

R

530

F

Summary

528 529

O

547

526 527

Béjot, Y., Mossiat, C., Giroud, M., Prigent-Tessier, A., Marie, C., 2011. Circulating and brain BDNF levels in stroke rats. Relevance to clinical studies. PLoS ONE 6, e29405. Benowitz, L.I., Perrone-Bizzozero, N.I., 2006. The relationship of GAP-43 to the development and plasticity of synaptic connections. Ann. N. Y. Acad. Sci. 627, 58–74. Benowitz, L.I., Routtenberg, A., 1997. GAP-43: an intrinsic determinant of neuronal development and plasticity. Trends Neurosci. 20, 84–91. Berti, R., Williams, A.J., Moffett, J.R., Hale, S.L., Velarde, L.C., Elliott, P.J., Yao, C., Dave, J.R., Tortella, F.C., 2002. Quantitative real-time RT-PCR analysis of inflammatory gene expression associated with ischemia-reperfusion brain injury. J. Cereb. Blood Flow Metab. 22, 1068–1079. Biernaskie, J., Corbett, D., 2001. Enriched rehabilitative training promotes improved forelimb motor function and enhanced dendritic growth after focal ischemic. Injury 1–9. Block, F., Dihne, M., Loos, M., 2005. Inflammation in areas of remote changes following focal brain lesion. Prog. Neurobiol. 75, 342–365. Bomze, H.M., Bulsara, K.R., Iskandar, B.J., Caroni, P., Skene, J.H., 2001. Spinal axon regeneration evoked by replacing two growth cone proteins in adult neurons. Nat. Neurosci. 4, 38–43. Bradbury, E.J., Khemani, S., Von, R., King, Priestley, J.V., McMahon, S.B., 1999. NT-3 promotes growth of lesioned adult rat sensory axons ascending in the dorsal columns of the spinal cord. Eur. J. Neurosci. 11, 3873–3883. Bregman, B.S., McAtee, M., Dai, H.N., Kuhn, P.L., 1997. Neurotrophic factors increase axonal growth after spinal cord injury and transplantation in the adult rat. Exp. Neurol. 148, 475–494. Brott, T., Marler, J.R., Olinger, C.P., Adams, H.P., Tomsick, T., Barsan, W.G., Biller, J., Eberle, R., Hertzberg, V., Walker, M., 1989. Measurements of acute cerebral infarction: lesion size by computed tomography. Stroke 20, 871–875. Brown, C.E., Murphy, T.H., 2007. Livin' on the edge: imaging dendritic spine turnover in the peri-infarct zone during ischemic stroke and recovery. Neuroscientist 14, 139–146. Brown, C.E., Li, P., Boyd, J.D., Delaney, K.R., Murphy, T.H., 2007. Extensive turnover of dendritic spines and vascular remodeling in cortical tissues recovering from stroke. J. Neurosci. 27, 4101–4109. Brown, C.E., Aminoltejari, K., Erb, H., Winship, I.R., Murphy, T.H., 2009a. In vivo voltagesensitive dye imaging in adult mice reveals that somatosensory maps lost to stroke are replaced over weeks by new structural and functional circuits with prolonged modes of activation within both the peri-infarct zone and distant sites. J. Neurosci. 29, 1719–1734. Brown, C.E., Boyd, J.D., Murphy, T.H., 2009b. Longitudinal in vivo imaging reveals balanced and branch-specific remodeling of mature cortical pyramidal dendritic arbors after stroke. J. Cereb. Blood Flow Metab. 30, 783–791. Browning, J.L., Widmayer, M.A., Hoffmann, K.K., Dudley, A.W., Baskin, D.S., 1996. Timedependent variability of infarct size and hemispheric volume in experimental focal cerebral ischemia in the rabbit. J. Neurotrauma 13, 583–588. Butefisch, C.M., 2003. Remote changes in cortical excitability after stroke. Brain 126, 470–481. Calautti, C., Jones, P.S., Naccarato, M., Sharma, N., Day, D.J., Bullmore, E.T., Warburton, E.A., Baron, J.C., 2010. The relationship between motor deficit and primary motor cortex hemispheric activation balance after stroke: longitudinal fMRI study. J. Neurol. Neurosurg. Psychiatry 81, 788–792. Carmichael, S.T., 2003. Plasticity of cortical projections after stroke. Neuroscientist 9, 64–75. Carmichael, S.T., 2012. Brain excitability in stroke: the yin and yang of stroke progression. Arch. Neurol. 69, 161–167. Carmichael, S.T., Wei, L., Rovainen, C.M., Woolsey, T.A., 2001. New patterns of intracortical projections after focal cortical stroke. Neurobiol. Dis. 8, 910–922. Carmichael, S.T., Archibeque, I., L L., Nolan, T., Momiy, J., Li, S., 2005. Growth-associated gene expression after stroke: evidence for a growth-promoting region in periinfarct cortex. Exp. Neurol. 193, 291–311. Castro-Alamancos, M.A., Borrel, J., 1995. Functional recovery of forelimb response capacity after forelimb primary motor cortex damage in the rat is due to the reorganization of adjacent areas of cortex. Neuroscience 68, 793–805. Cicinelli, P., Traversa, R., Rossini, P.M., 1997. Post-stroke reorganization of brain motor output to the hand: a 2–4 month follow-up with focal magnetic transcranial stimulation. Electroencephalogr. Clin. Neurophysiol. 105, 438–450. Clarkson, A.N., Overman, J.J., Zhong, S., Mueller, R., Lynch, G., Carmichael, S.T., 2011. AMPA receptor-induced local brain-derived neurotrophic factor signaling mediates motor recovery after stroke. J. Neurosci. 31, 3766–3775. Clausen, B.H., Lambertsen, K.L., Babcock, A.A., Holm, T.H., Dagnaes-Hansen, F., Finsen, B., 2008. Interleukin-1beta and tumor necrosis factor-alpha are expressed by different subsets of microglia and macrophages after ischemic stroke in mice. J. Neuroinflammation 5, 46. Conner, J.M., Chiba, A.A., Tuszynski, M.H., 2005. The basal forebrain cholinergic system is essential for cortical plasticity and functional recovery following brain injury. Neuron 46, 173–179. Dancause, N., 2005. Extensive cortical rewiring after brain injury. J. Neurosci. 25, 10167–10179. Danton, G.H., Dietrich, W.D., 2003. Inflammatory mechanisms after ischemia and stroke. J. Neuropathol. Exp. Neurol. 62, 127–136. Dent, E.W., Meiri, K.F., 1992. GAP-43 phosphorylation is dynamically regulated in individual growth cones. J. Neurobiol. 23, 1037–1053. DeVetten, G., Coutts, S.B., Hill, M.D., Goyal, M., Eesa, M., O'Brien, B., Demchuk, A.M., Kirton, A., for the MONITOR and VISION study groups, 2010. Acute corticospinal tract Wallerian degeneration is associated with stroke outcome. Stroke 41, 751–756.

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and blocking local BDNF function in periinfarct cortex prevents this AMPA receptor-mediated recovery (Clarkson et al., 2011). After traumatic injury of sensorimotor cortex, CST axons from the uninjured hemisphere sprout into the denervated side of the cervical spinal cord, forming functional synaptic connections with segmental and propriospinal spinal interneurons and contributing to spontaneous recovery (M. Ueno et al., 2012). Notably, knockdown of BDNF in the spinal neurons or its receptor in the intact corticospinal neurons reduced sprouting of the CST and impaired recovery (M. Ueno et al., 2012). Our data reveal a transient increase in BDNF expression in CSC three days after cortical stroke (preceding increased GAP-43 expression), suggesting that BDNF may be important as a local signal for initiating structural plasticity in the cord. NT-3 is a neurotrophic factor found in motor neurons in the spinal cord that acts as a chemoattractant to guide regenerating axons and neuritis after injury (Alto et al., 2009; Ernfors and Persson, 1991; Hajebrahimi et al., 2008; Lindvall et al., 1992; Yang et al., 1998). Our data showed a trend toward an increase in NT-3 protein expression in the CSC after complete FL-SMC. Notably, the temporal profile of NT-3 protein expression was highly correlated with GAP-43 expression in the CSC. In concert with changes in IL-6, TNF-α, and BDNF levels, this local change in NT-3 may act as a chemoattractant for sprouting axons during periods of heightened spinal plasticity.

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LaPash Daniels, C.M., Ayers, K.L., Finley, A.M., Culver, J.P., Goldberg, M.P., 2009. Axon sprouting in adult mouse spinal cord after motor cortex stroke. Neurosci. Lett. 450, 191–195. Larsson, E., Nanobashvili, A., Kokaia, Z., Lindvall, O., 1999. Evidence for neuroprotective effects of endogenous brain-derived neurotrophic factor after global forebrain ischemia in rats. J. Cereb. Blood Flow Metab. 19, 1220–1228. Leu, B., Koch, E., Schmidt, J.T., 2010. GAP43 phosphorylation is critical for growth and branching of retinotectal arbors in zebrafish. Dev. Neurobiol. 70, 897–911. Li, Y., Jiang, N., Powers, C., Chopp, M., Johansson, B.B., 1998. Neuronal damage and plasticity identified by microtubule-associated protein 2, growth-associated protein 43, and cyclin D1 immunoreactivity after focal cerebral ischemia in rats editorial comment. Stroke 29, 1972–1981. Liepert, J., Miltner, W.H., Bauder, H., Sommer, M., Dettmers, C., Taub, E., Weiller, C., 1998. Motor cortex plasticity during constraint-induced movement therapy in stroke patients. Neurosci. Lett. 250, 5–8. Liepert, J., Bauder, H., Miltner, W.H.R., Taub, E., Weiller, C., 2000. Treatment-induced cortical reorganization after stroke in humans. Stroke 31, 1210–1216. Lindvall, O., Ernfors, P., Bengzon, J., Kokaia, Z., Smith, M.L., Siesjö, B.K., Persson, H., 1992. Differential regulation of mRNAs for nerve growth factor, brain-derived neurotrophic factor, and neurotrophin 3 in the adult rat brain following cerebral ischemia and hypoglycemic coma. Proc. Natl. Acad. Sci. U. S. A. 89, 648–652. Liu, Z., Li, Y., Qu, R., Shen, L., Gao, Q., Zhang, X., Lu, M., Savant-Bhonsale, S., Borneman, J., Chopp, M., 2007. Axonal sprouting into the denervated spinal cord and synaptic and postsynaptic protein expression in the spinal cord after transplantation of bone marrow stromal cell in stroke rats. Brain Res. 1149, 172–180. Liu, Z., Li, Y., Zhang, X., Savant-Bhonsale, S., Chopp, M., 2008. Contralesional axonal remodeling of the corticospinal system in adult rats after stroke and bone marrow stromal cell treatment. Stroke 39, 2571–2577. Liu, Z., Zhang, R.L., Li, Y., Cui, Y., Chopp, M., 2009. Remodeling of the corticospinal innervation and spontaneous behavioral recovery after ischemic stroke in adult mice. Stroke 40, 2546–2551. Liu, Z., Li, Y., Zhang, L., Xin, H., Cui, Y., Hanson, L.R., Frey II, W.H., Chopp, M., 2012. Subacute intranasal administration of tissue plasminogen activator increases functional recovery and axonal remodeling after stroke in rats. Neurobiol. Dis. 45, 804–809. Loos, M., Dihne, M., Block, F., 2003. Tumor necrosis factor-α expression in areas of remote degeneration following middle cerebral artery occlusion of the rat. Neuroscience 122, 373–380. Maddahi, A., Kruse, L.S., Chen, Q.-W., Edvinsson, L., 2011. The role of tumor necrosis factor-α and TNF-α receptors in cerebral arteries following cerebral ischemia in rat. J. Neuroinflammation 8, 107. Madinier, A., Bertrand, N., Rodier, M., Quirié, A., Mossiat, C., Prigent-Tessier, A., Marie, C., Garnier, P., 2013. Ipsilateral versus contralateral spontaneous post-stroke neuroplastic changes: Involvement of BDNF? Neuroscience 231, 169–181. Manganotti, P., Acler, M., Zanette, G.P., Smania, N., Fiaschi, A., 2007. Motor cortical disinhibition during early and late recovery after stroke. Neurorehabil. Neural Repair 22, 396–403. Marchetti, L., 2004. Tumor necrosis factor (TNF)-mediated neuroprotection against glutamate-induced excitotoxicity is enhanced by N-methyl-D-aspartate receptor activation: essential role of a TNF receptor 2-mediated phosphatidylinositol-3kinase-dependent NF-B pathway. J. Biol. Chem. 279, 32869–32881. Montoya, C.P., Campbell-Hope, L.J., Pemberton, K.D., Dunnett, S.B., 1991. The “staircase test”: a measure of independent forelimb reaching and grasping abilities in rats. J. Neurosci. Methods 36, 219–228. Murphy, T.H., Corbett, D., 2009. Plasticity during stroke recovery: from synapse to behaviour. Nat. Rev. Neurosci. 10, 861–872. Nagappan, G., Lu, B., 2005. Activity-dependent modulation of the BDNF receptor TrkB: mechanisms and implications. Trends Neurosci. 28, 464–471. Nelson, T.E., Olde Engberink, A., Hernandez, R., Puro, A., Huitron-Resendiz, S., Hao, C., De Graan, P.N.E., Gruol, D.L., 2012. Altered synaptic transmission in the hippocampus of transgenic mice with enhanced central nervous systems expression of interleukin-6. Brain Behav. Immun. 26, 959–971. Ng, S.C., de la Monte, S.M., Conboy, G.L., Karns, L.R., Fishman, M.C., 1988. Cloning of human GAP-43: growth association and ischemic resurgence. Neuron 1, 133–139. O'Connor, J.J., 2013. Targeting tumour necrosis factor-α in hypoxia and synaptic signalling. Ir. J. Med. Sci. 182, 157–162. Omoto, S., Ueno, M., Mochio, S., Yamashita, T., 2011. Corticospinal tract fibers cross the ephrin-B3-negative part of the midline of the spinal cord after brain injury. Neurosci. Res. 69, 187–195. Oshima, T., Lee, S., Sato, A., Oda, S., Hirasawa, H., Yamashita, T., 2009. TNF-alpha contributes to axonal sprouting and functional recovery following traumatic brain injury. Brain Res. 1290, 102–110. Pagnussat, A.S., Simao, F., Anastacio, J.R., Mestriner, R.G., Michaelsen, S.M., Castro, C.C., Salbego, C., Netto, C.A., 2012. Effects of skilled and unskilled training on functional recovery and brain plasticity after focal ischemia in adult rats. Brain Res. 1486, 53–61. Parish, C.L., Finkelstein, D.I., Tripanichkul, W., Satoskar, A.R., Drago, J., Horne, M.K., 2002. The role of interleukin-1, interleukin-6, and glia in inducing growth of neuronal terminal arbors in mice. J. Neurosci. 22, 8034–8041. Paxinos, G., Watson, C., 2007. The rat brain in stereotaxic coordinates. Ploughman, M., Windle, V., MacLellan, C.L., White, N., Doré, J.J., Corbett, D., 2009. Brainderived neurotrophic factor contributes to recovery of skilled reaching after focal ischemia in rats. Stroke 40, 1490–1495. Pribiag, H., Stellwagen, D., 2013. TNF-α downregulates inhibitory neurotransmission through protein phosphatase 1-dependent trafficking of GABAA receptors. J. Neurosci. 33, 15879–15893. Puig, J., Pedraza, S., Blasco, G., Daunis-I-Estadella, J., Prats, A., Prados, F., Boada, I., Castellanos, M., Sánchez-González, J., Remollo, S., Laguillo, G., Quiles, A.M., Gómez,

E

T

Di Giovanni, S., Knoblach, S.M., Brandoli, C., Aden, S.A., Hoffman, E.P., Faden, A.I., 2003. Gene profiling in spinal cord injury shows role of cell cycle in neuronal death. Ann. Neurol. 53, 454–468. Dijkhuizen, R.M.R., Ren, J.J., Mandeville, J.B.J., Wu, O.O., Ozdag, F.M.F., Moskowitz, M.A.M., Rosen, B.R.B., Finklestein, S.P.S., 2001. Functional magnetic resonance imaging of reorganization in rat brain after stroke. Proc. Natl. Acad. Sci. U. S. A. 98, 12766–12771. Dirnagl, U., Iadecola, C., 1999. Pathobiology of ischaemic stroke: an integrated view. Trends Neurosci. Ernfors, P., Persson, H., 1991. Developmentally regulated expression of HDNF/NT-3 mRNA in rat spinal cord motoneurons and expression of BDNF MRNA in embryonic dorsal root ganglion. Eur. J. Neurosci. 3, 953–961. Ernfors, P., Wetmore, C., Olson, L., Persson, H., 1990. Identification of cells in rat brain and peripheral tissues expressing mRNA for members of the nerve growth factor family. Neuron 5, 511–526. Frey, D., Laux, T., Xu, L., Schneider, C., Caroni, P., 2000. Shared and unique roles of CAP23 and GAP43 in actin regulation, neurite outgrowth, and anatomical plasticity. J. Cell Biol. 149, 1443–1454. Fridman, E.A., 2004. Reorganization of the human ipsilesional premotor cortex after stroke. Brain 127, 747–758. Frost, S.B., 2003. Reorganization of remote cortical regions after ischemic brain injury: a potential substrate for stroke recovery. J. Neurophysiol. 89, 3205–3214. Fujii, Y., Nakada, T., 2003. Cortical reorganization in patients with subcortical hemiparesis: neural mechanisms of functional recovery and prognostic implication. J. Neurosurg. 98, 64–73. Gharbawie, O.A., Gonzalez, C.L.R., Williams, P.T., Kleim, J.A., Whishaw, I.Q., 2005. Middle cerebral artery (MCA) stroke produces dysfunction in adjacent motor cortex as detected by intracortical microstimulation in rats. Neuroscience 130, 601–610. Grill, R., Murai, K., Blesch, A., Gage, F.H., Tuszynski, M.H., 1997. Cellular delivery of neurotrophin-3 promotes corticospinal axonal growth and partial functional recovery after spinal cord injury. J. Neurosci. 17, 5560–5572. Hajebrahimi, Z., Mowla, S.J., Movahedin, M., Tavallaei, M., 2008. Gene expression alterations of neurotrophins, their receptors and prohormone convertases in a rat model of spinal cord contusion. Neurosci. Lett. 441, 261–266. Hakkoum, D., Stoppini, L., Muller, D., 2007. Interleukin-6 promotes sprouting and functional recovery in lesioned organotypic hippocampal slice cultures. J. Neurochem. 100, 747–757. Hammond, E.N., Tetzlaff, W., Mestres, P., Giehl, K.M., 1999. BDNF, but not NT-3, promotes long-term survival of axotomized adult rat corticospinal neurons in vivo. Neuroreport 10, 2671–2675. Hayashi, M., Ueyama, T., Nemoto, K., Tamaki, T., Senba, E., 2000. Sequential mRNA expression for immediate early genes, cytokines, and neurotrophins in spinal cord injury. J. Neurotrauma 17, 203–218. He, Q., Dent, E.W., Meiri, K.F., 1997. Modulation of actin filament behavior by GAP-43 (neuromodulin) is dependent on the phosphorylation status of serine 41, the protein kinase C site. J. Neurosci. 17, 3515–3524. Hill, J.K., Gunion-Rinker, L., Kulhanek, D., Lessov, N., Kim, S., Clark, W.M., Dixon, M.P., Nishi, R., Stenzel-Poore, M.P., Eckenstein, F.P., 1999. Temporal modulation of cytokine expression following focal cerebral ischemia in mice. Brain Res. 820, 45–54. Hoffman, P.N., 1989. Expression of GAP-43, a rapidly transported growth-associated protein, and class II beta tubulin, a slowly transported cytoskeletal protein, are coordinated in regenerating neurons. J. Neurosci. 9, 893–897. Hohn, A., Leibrock, J., Bailey, K., Barde, Y.A., 1990. Identification and characterization of a novel member of the nerve growth factor/brain-derived neurotrophic factor family. Nature 344, 339–341. Horch, H.W., Katz, L.C., 2002. BDNF release from single cells elicits local dendritic growth in nearby neurons. Nat. Neurosci. 5, 1177–1184. Hsu, J.E., Jones, T.A., 2006. Contralesional neural plasticity and functional changes in the less-affected forelimb after large and small cortical infarcts in rats. Exp. Neurol. 201, 479–494. Iizuka, H., Sakatani, K., Young, W., 2005. Neural damage in the rat thalamus after cortical infarcts. Stroke 1–6. Jacobson, R.D., Virag, I., Skene, J.H., 1986. A protein associated with axon growth, GAP-43, is widely distributed and developmentally regulated in rat CNS. J. Neurosci. 6, 1843–1855. Jayaram, G., Stagg, C.J., Esser, P., Kischka, U., Stinear, J., Johansen-Berg, H., 2012. Relationships between functional and structural corticospinal tract integrity and walking post stroke. Clin. Neurophysiol. 1–7. Johansen-Berg, H., Dawes, H., Guy, C., Smith, S.M., Wade, D.T., Matthews, P.M., 2002a. Correlation between motor improvements and altered fMRI activity after rehabilitative therapy. Brain 125, 2731–2742. Johansen-Berg, H., Rushworth, M.F.S., Bogdanovic, M.D., Kischka, U., Wimalaratna, S., Matthews, P.M., 2002b. The role of ipsilateral premotor cortex in hand movement after stroke. Proc. Natl. Acad. Sci. U. S. A. 99, 14518–14523. Johnston, D.G., Denizet, M., Mostany, R., Portera-Cailliau, C., 2012. Chronic in vivo imaging shows no evidence of dendritic plasticity or functional remapping in the contralesional cortex after stroke. Cereb. Cortex. Kataoka, K., Hayakawa, T., Yamada, K., Mushiroi, T., Kuroda, R., Mogami, H., 1989. Neuronal network disturbance after focal ischemia in rats. Stroke 20, 1226–1235. Kokaia, Z., Zhao, Q., Kokaia, M., Elmér, E., Metsis, M., Smith, M.L., Siesjö, B.K., Lindvall, O., 1995. Regulation of brain-derived neurotrophic factor gene expression after transient middle cerebral artery occlusion with and without brain damage. Exp. Neurol. 136, 73–88. Lama, S., Qiao, M., Kirton, A., Sun, S., Cheng, E., Foniok, T., Tuor, U.I., 2011. Imaging corticospinal degeneration in neonatal rats with unilateral cerebral infarction. Exp. Neurol. 1–8. Lambertsen, K.L., Biber, K., Finsen, B., 2012. Inflammatory cytokines in experimental and human stroke. J. Cereb. Blood Flow Metab. 32, 1677–1698.

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Please cite this article as: Sist, B., et al., Plasticity beyond peri-infarct cortex: Spinal up regulation of structural plasticity, neurotrophins, and inflammatory cytokines during recovery from cortical stroke, Exp. Neurol. (2013), http://dx.doi.org/10.1016/j.expneurol.2013.11.019

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D

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O

F

Ueno, M., Hayano, Y., Nakagawa, H., Yamashita, T., 2012a. Intraspinal rewiring of the corticospinal tract requires target-derived brain-derived neurotrophic factor and compensates lost function after brain injury. Brain 135, 1253–1267. Ueno, Y., Chopp, M., Zhang, L., Buller, B., Liu, Z., Lehman, N.L., Liu, X.S., Zhang, Y., Roberts, C., Zhang, Z.G., 2012b. Axonal outgrowth and dendritic plasticity in the cortical periinfarct area after experimental stroke. Stroke 43, 2221–2228. Uno, H., Matsuyama, T., Akita, H., Nishimura, H., Sugita, M., 1997. Induction of tumor necrosis factor-α in the mouse hippocampus following transient forebrain ischemia. J. Cereb. Blood Flow Metab. 17, 491–499. van Meer, M.P.A., Otte, W.M., van der Marel, K., Nijboer, C.H., Kavelaars, A., van der Sprenkel, J.W.B., Viergever, M.A., Dijkhuizen, R.M., 2012. Extent of bilateral neuronal network reorganization and functional recovery in relation to stroke severity. J. Neurosci. 32, 4495–4507. Vavrek, R., Girgis, J., Tetzlaff, W., Hiebert, G.W., Fouad, K., 2006. BDNF promotes connections of corticospinal neurons onto spared descending interneurons in spinal cord injured rats. Brain 129, 1534–1545. Wang, Q., Tang, X.N., Yenari, M.A., 2007. The inflammatory response in stroke. J. Neuroimmunol. 184, 53–68. Wang, L.E., Tittgemeyer, M., Imperati, D., Diekhoff, S., Ameli, M., Fink, G.R., Grefkes, C., 2012. Degeneration of corpus callosum and recovery of motor function after stroke: a multimodal magnetic resonance imaging study. Hum. Brain Mapp. 33, 2941–2956. Watson, B.D., Dietrich, W.D., Busto, R., Wachtel, M.S., Ginsberg, M.D., 1985. Induction of reproducible brain infarction by photochemically initiated thrombosis. Ann. Neurol. 17, 497–504. Watters, O., O'Connor, J.J., 2011. A role for tumor necrosis factor-α in ischemia and ischemic preconditioning. J. Neuroinflammation 8, 87. Weishaupt, N., Silasi, G., Colbourne, F., Fouad, K., 2010. Secondary damage in the spinal cord after motor cortex injury in rats. J. Neurotrauma 27, 1387–1397. Weishaupt, N., Li, S., Di Pardo, A., Sipione, S., Fouad, K., 2013. Synergistic effects of BDNF and rehabilitative training on recovery after cervical spinal cord injury. Behav. Brain Res. 239, 31–42. Winship, I.R., Murphy, T.H., 2008. In vivo calcium imaging reveals functional rewiring of single somatosensory neurons after stroke. J. Neurosci. 28, 6592–6606. Winship, I.R., Murphy, T.H., 2009. Remapping the somatosensory cortex after stroke: insight from imaging the synapse to network. Neuroscientist 15, 507–524. Yang, K., Perez Polo, J.R., Mu, X.S., Yan, H.Q., Xue, J.J., Iwamoto, Y., Liu, S.J., Dixon, C.E., Hayes, R.L., 1998. Increased expression of brain‐derived neurotrophic factor but not neurotrophin‐3 mRNA in rat brain after cortical impact injury. J. Neurosci. Res. 44, 157–164. Yang, P., Wen, H., Ou, S., Cui, J., Fan, D., 2012. IL-6 promotes regeneration and functional recovery after cortical spinal tract injury by reactivating intrinsic growth program of neurons and enhancing synapse formation. Exp. Neurol. 236, 19–27. Ye, J.H., Houle, J.D., 1997. Treatment of the chronically injured spinal cord with neurotrophic factors can promote axonal regeneration from supraspinal neurons. Exp. Neurol. 143, 70–81. Yoshii, A., Constantine-Paton, M., 2010. Postsynaptic BDNF-TrkB signaling in synapse maturation, plasticity, and disease. Dev. Neurobiol. (NA–NA). Yu, C., Zhu, C., Zhang, Y., Chen, H., Qin, W., Wang, M., Li, K., 2009. A longitudinal diffusion tensor imaging study on Wallerian degeneration of corticospinal tract after motor pathway stroke. NeuroImage 47, 451–458. Zeiler, S.R., Gibson, E.M., Hoesch, R.E., Li, M.Y., Worley, P.F., O'Brien, R.J., Krakauer, J.W., 2013. Medial premotor cortex shows a reduction in inhibitory markers and mediates recovery in a mouse model of focal stroke. Stroke 44, 483–489. Zhang, Y., Xiong, Y., Mahmood, A., Meng, Y., Liu, Z., Qu, C., Chopp, M., 2010. Sprouting of corticospinal tract axons from the contralateral hemisphere into the denervated side of the spinal cord is associated with functional recovery in adult rat after traumatic brain injury and erythropoietin treatment. Brain Res. 1353, 249–257. Zheng, J., Liu, L., Xue, X., Li, H., Wang, S., Cao, Y., Zhao, J., 2013. Cortical electrical stimulation promotes neuronal plasticity in the peri-ischemic cortex and contralesional anterior horn of cervical spinal cord in a rat model of focal cerebral ischemia. Brain Res. 1–9. Zuber, M.X., Goodman, D.W., Karns, L.R., Fishman, M.C., 1989. The neuronal growthassociated protein GAP-43 induces filopodia in non-neuronal cells. Science 244, 1193–1195.

T

C

E

R

R

O

C

N

973

E., Serena, J., 2010. Wallerian degeneration in the corticospinal tract evaluated by diffusion tensor imaging correlates with motor deficit 30 days after middle cerebral artery ischemic stroke. AJNR Am. J. Neuroradiol. 31, 1324–1330. Que, M., Schiene, K., Witte, O.W., Zilles, K., 1999. Widespread up-regulation of N-methylD-aspartate receptors after focal photothrombotic lesion in rat brain. Neurosci. Lett. 273, 77–80. Ramic, M., Emerick, A.J., Bollnow, M.R., O'Brien, T.E., Tsai, S.-Y., Kartje, G.L., 2006. Axonal plasticity is associated with motor recovery following amphetamine treatment combined with rehabilitation after brain injury in the adult rat. Brain Res. 1111, 176–186. Reitmeir, R., Kilic, E., Kilic, U., Bacigaluppi, M., ElAli, A., Salani, G., Pluchino, S., Gassmann, M., Hermann, D.M., 2011. Post-acute delivery of erythropoietin induces stroke recovery by promoting perilesional tissue remodelling and contralesional pyramidal tract plasticity. Brain 134, 84–99. Rocamora, N., Palacios, J.M., Mengod, G., 1992. Limbic seizures induce a differential regulation of the expression of nerve growth factor, brain-derived neurotrophic factor and neurotrophin-3, in the rat hippocampus. Brain Res. Mol. Brain Res. 13, 27–33. Saleh, A., Smith, D.R., Balakrishnan, S., Dunn, L., Martens, C., Tweed, C.W., Fernyhough, P., 2011. Tumor necrosis factor-α elevates neurite outgrowth through an NF-κBdependent pathway in cultured adult sensory neurons: diminished expression in diabetes may contribute to sensory neuropathy. Brain Res. 1423, 87–95. Santello, M., Bezzi, P., Volterra, A., 2011. TNFα controls glutamatergic gliotransmission in the hippocampal dentate gyrus. Neuron 69, 988–1001. Schaechter, J.D., 2006. Structural and functional plasticity in the somatosensory cortex of chronic stroke patients. Brain 129, 2722–2733. Schiene, K., Bruehl, C., Zilles, K., Qü, M., Hagemann, G., Kraemer, M., Witte, O.W., 1996. Neuronal hyperexcitability and reduction of GABAA-receptor expression in the surround of cerebral photothrombosis. J. Cereb. Blood Flow Metab. 16, 906–914. Schnell, L., Schneider, R., Kolbeck, R., Barde, Y.A., Schwab, M.E., 1994. Neurotrophin-3 enhances sprouting of corticospinal tract during development and after adult spinal cord lesion. Nature 367, 170–173. Shanina, E.V., Redecker, C., Reinecke, S., Schallert, T., Witte, O.W., 2005. Long-term effects of sequential cortical infarcts on scar size, brain volume and cognitive function. Behav. Brain Res. 158, 69–77. Sist, B., Jesudasan, S.J.B., Winship, I.R., 2012. Diaschisis, degeneration, and adaptive plasticity after focal ischemic. Stroke. Skene, J.H.P., 1989. Axonal growth-associated proteins. Annu. Rev. Neurosci. 12, 127–156. Song, G., Cechvala, C., Resnick, D.K., Dempsey, R.J., Rao, V.L., 2001. GeneChip analysis after acute spinal cord injury in rat. J. Neurochem. 79, 804–815. Stammers, A.T., Liu, J., Kwon, B.K., 2011. Expression of inflammatory cytokines following acute spinal cord injury in a rodent model. J. Neurosci. Res. 90, 782–790. Starkey, M.L., Bleul, C., Maier, I.C., Schwab, M.E., 2011. Rehabilitative training following unilateral pyramidotomy in adult rats improves forelimb function in a non-task specific way. Exp. Neurol. 1–9. Starkey, M.L., Bartus, K., Barritt, A.W., Bradbury, E.J., 2012. Chondroitinase ABC promotes compensatory sprouting of the intact corticospinal tract and recovery of forelimb function following unilateral pyramidotomy in adult mice. Eur. J. Neurosci. 36, 3665–3678. Stroemer, R.P., Kent, T.A., Hulsebosch, C.E., 1995. Neocortical neural sprouting, synaptogenesis, and behavioral recovery after neocortical infarction in rats. Stroke 26, 2135–2144. Sulejczak, D., Ziemlińska, E., Czarkowska-Bauch, J., Nosecka, E., Strzalkowski, R., Skup, M., 2007. Focal photothrombotic lesion of the rat motor cortex increases BDNF levels in motor-sensory cortical areas not accompanied by recovery of forelimb motor skills. J. Neurotrauma 24, 1362–1377. Suzuki, S., Tanaka, K., Suzuki, N., 2008. Ambivalent aspects of interleukin-6 in cerebral ischemia: inflammatory versus neurotrophic aspects. J. Cereb. Blood Flow Metab. 29, 464–479. Takatsuru, Y., Fukumoto, D., Yoshitomo, M., Nemoto, T., Tsukada, H., Nabekura, J., 2009. Neuronal circuit remodeling in the contralateral cortical hemisphere during functional recovery from cerebral infarction. J. Neurosci. 29, 10081–10086. Thomalla, G., Glauche, V., KOCH, M., BEAULIEU, C., Weiller, C., Rother, J., 2004. Diffusion tensor imaging detects early Wallerian degeneration of the pyramidal tract after ischemic stroke. NeuroImage 22, 1767–1774. Turrin, N.P., 2006. Tumor necrosis factor but not interleukin 1 mediates neuroprotection in response to acute nitric oxide excitotoxicity. J. Neurosci. 26, 143–151.

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