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Neuroscience Letters, 128 (1991) 57~0 Elsevier Scientific Publishers Ireland Ltd. ADONIS 030439409100330C NSL 07846
Differential neuropeptide expression after visceral and somatic nerve injury in the cat and rat P. A n a n d 1, M . A . G h a t e i 1, N . D . Christofides 1, M . A . Blank 1, G.P. M c G r e g o r 1, J.F.B. M o r r i s o n 2, F. Scaravilli 3 a n d S.R. B l o o m 1 1Department of Medicine, Hammersmith Hospital, London ( U.K. ) , 2Department of Physiology, Leeds University, Leeds ( U.K.) and aDepartment of Neuropathology, National Hospital, Queen Square, London ( U.K. ) (Received 10 December 1990; Revised version received I0 February 1991; Accepted 3 April 1991)
Key words: Neuropeptide; Somatic nerve; Visceral nerve; Nerve injury The expression of neuropeptides galanin, vasoactive intestinal polypeptide (VIP) and substance P was compared after injury to somatic (sciatic, pudendal) and visceral (pelvic) nerves. Studies in normal rats and the mutant rat 'mutilated foot' suggested that galanin increases in sensory but not sympathetic fibres after sciatic nerve injury, while VIP appears to increase in both sensory and sympathetic fibres, and substance P to decrease in sensory fibres. A direct comparison of neuropeptide changes after somatic and visceral nerve injury was made in the cat dorsal sacral spinal cord, where both pudendal (somatic) and pelvic (visceral) afferents terminate. Four weeks after pudendal nerve transection in the cat there was an increase of VIP and galanin but decrease of substance P in the dorsal sacral cord, similar to the changes in lumbar dorsal cord after sciatic nerve section in the rat. In contrast, 4 weeks after pelvic nerve transection in the cat, galanin was unchanged in the ipsilateral dorsal sacral spinal cord, whereas VIP is known to decrease markedly and substance P to remain unchanged. There is thus differential peptide expression before and after injury in somatic and visceral systems, which may be regulated in part by the target organ. We have proposed that the neuropeptide changes occur in neurons that regulate development, maintenance and repair after injury, processes that may differ in somatic and visceral systems.
Neuropeptide expression changes in nerve fibres after injury: two weeks after sciatic nerve transection in the rat, there is decreased substance P but increased vasoactive intestinal polypeptide (VIP) both in the injured nerve and in the ipsilateral dorsal spinal cord where the injured fibres terminate [4, 16, 19]. A study of galanin immunoreactivity in the mammalian central nervous system demonstrated that it was present in primary sensory fibres, and that a neuronal pathway originating in the rat sacral spinal cord may increase galanin expression after injury [9]. There was also increased galanin expression in primary sensory fibres in the rat after sciatic nerve injury [14, 24]. Thus galanin expression appeared to increase in a manner similar to VIP expression after rat spinal cord [11] and sciatic nerve injury [4, 6, 19, 23]. This study had two related aims. First, to ascertain whether galanin expression in injured peripheral fibres always paralleled VIP expression. Second, to see if there was a different response of afferents containing these neuropeptides in somatic and visceral systems. As the increased VIP expression in injured rat sciatic nerve may occur in both sensory and sympathetic fibres [6], we stuCorrespondence: S.R. Bloom, Department of Medicine, Hammersmith Hospital, Du Cane Road, London W12 OHS, U.K.
died the origin of the fibres expressing galanin after injury in normal rats, and in the mutant 'mutilated foot' (mf) rat, which has a selective loss of sensory fibres [15]. A further comparison of galanin and VIP expression in injured primary afferent fibres was made in the cat. VIP is present in pelvic nerve primary afferent fibres in the lumbosacral spinal cord of man [5] and cat [3, 12, 13]. In contrast to the response of primary afferent fibres in rat sciatic nerve, there was evidence of decreased VIP expression in cat pelvic nerve afferents after peripheral axotomy [13]. The suggestion that visceral (pelvic) afterents may differ from somatic (sciatic and pudendal) afferent fibres in their response to injury led to this study of peptide expression in dorsal sacral spinal cord of the cat after pelvic and pudendal nerve transection. Pelvic and pudendal nerve peptide-containing afferents terminate in the same segments of the cat dorsal sacral spinal cord, and changes in their expression of neuropeptides may be more easily studied here than in the periphery. In the first experiment, a group of neonatal Wistar rats (n = 6) were treated with capsaicin (Sigma) systemically two days after birth (50 mg/kg s.c.), which produces a marked selective depletion of unmyelinated afferent fibres [21]; their littermates (n=4) received saline, and served as controls. In the second experiment
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another group of Wistar rats (n=6) were sympathectomised with 6-hydroxydopamine (6-OHDA, Sigma): each rat received 150/zg/g s.c. daily for the first 14 days after birth [12]. The sympthectomised rats showed ptosis, and had a complete loss of catecholamine-staining fibres innervating sciatic nerve vasa nervorum [6]. Control litter mates (n = 4) received saline in the same protocol. In the third experiment, adult mf rats (n = 4) were used, with Sprague-Dawley rats as controls (n =4). All rats were anaesthetized with ether and the right sciatic nerve ligated and transected in the midthigh region. The nerve distal to the ligation was avulsed. The capsaicintreated rats and their controls were operated at the age of 6 weeks, and the sympathectomised rats at the age of two weeks. The rats were sacrificed with an ether overdose two weeks after nerve transection. Peptides were extracted by boiling fresh tissues in 0.5 M acetic acid (1: l 0, w/v). Duplicate aliquots were assayed for galanin, VIP and substance P by sensitive and specific radioimmunoassays, and chromatographic analyses of the immunoreactivities were similar to those previously described [9, 19]. There was a marked increase of galanin content in the terminal 0.5-cm nerve stump when compared to intact nerve, whereas there was a fall of substance P (see Table I for all rat nerve data). Capsaicin pretreatment produced a depletion of substance P in uninjured nerves (P
Neuroscience Letters, 128 (1991) 57~0 Elsevier Scientific Publishers Ireland Ltd. ADONIS 030439409100330C NSL 07846
Differential neuropeptide expression after visceral and somatic nerve injury in the cat and rat P. A n a n d 1, M . A . G h a t e i 1, N . D . Christofides 1, M . A . Blank 1, G.P. M c G r e g o r 1, J.F.B. M o r r i s o n 2, F. Scaravilli 3 a n d S.R. B l o o m 1 1Department of Medicine, Hammersmith Hospital, London ( U.K. ) , 2Department of Physiology, Leeds University, Leeds ( U.K.) and aDepartment of Neuropathology, National Hospital, Queen Square, London ( U.K. ) (Received 10 December 1990; Revised version received I0 February 1991; Accepted 3 April 1991)
Key words: Neuropeptide; Somatic nerve; Visceral nerve; Nerve injury The expression of neuropeptides galanin, vasoactive intestinal polypeptide (VIP) and substance P was compared after injury to somatic (sciatic, pudendal) and visceral (pelvic) nerves. Studies in normal rats and the mutant rat 'mutilated foot' suggested that galanin increases in sensory but not sympathetic fibres after sciatic nerve injury, while VIP appears to increase in both sensory and sympathetic fibres, and substance P to decrease in sensory fibres. A direct comparison of neuropeptide changes after somatic and visceral nerve injury was made in the cat dorsal sacral spinal cord, where both pudendal (somatic) and pelvic (visceral) afferents terminate. Four weeks after pudendal nerve transection in the cat there was an increase of VIP and galanin but decrease of substance P in the dorsal sacral cord, similar to the changes in lumbar dorsal cord after sciatic nerve section in the rat. In contrast, 4 weeks after pelvic nerve transection in the cat, galanin was unchanged in the ipsilateral dorsal sacral spinal cord, whereas VIP is known to decrease markedly and substance P to remain unchanged. There is thus differential peptide expression before and after injury in somatic and visceral systems, which may be regulated in part by the target organ. We have proposed that the neuropeptide changes occur in neurons that regulate development, maintenance and repair after injury, processes that may differ in somatic and visceral systems.
Neuropeptide expression changes in nerve fibres after injury: two weeks after sciatic nerve transection in the rat, there is decreased substance P but increased vasoactive intestinal polypeptide (VIP) both in the injured nerve and in the ipsilateral dorsal spinal cord where the injured fibres terminate [4, 16, 19]. A study of galanin immunoreactivity in the mammalian central nervous system demonstrated that it was present in primary sensory fibres, and that a neuronal pathway originating in the rat sacral spinal cord may increase galanin expression after injury [9]. There was also increased galanin expression in primary sensory fibres in the rat after sciatic nerve injury [14, 24]. Thus galanin expression appeared to increase in a manner similar to VIP expression after rat spinal cord [11] and sciatic nerve injury [4, 6, 19, 23]. This study had two related aims. First, to ascertain whether galanin expression in injured peripheral fibres always paralleled VIP expression. Second, to see if there was a different response of afferents containing these neuropeptides in somatic and visceral systems. As the increased VIP expression in injured rat sciatic nerve may occur in both sensory and sympathetic fibres [6], we stuCorrespondence: S.R. Bloom, Department of Medicine, Hammersmith Hospital, Du Cane Road, London W12 OHS, U.K.
died the origin of the fibres expressing galanin after injury in normal rats, and in the mutant 'mutilated foot' (mf) rat, which has a selective loss of sensory fibres [15]. A further comparison of galanin and VIP expression in injured primary afferent fibres was made in the cat. VIP is present in pelvic nerve primary afferent fibres in the lumbosacral spinal cord of man [5] and cat [3, 12, 13]. In contrast to the response of primary afferent fibres in rat sciatic nerve, there was evidence of decreased VIP expression in cat pelvic nerve afferents after peripheral axotomy [13]. The suggestion that visceral (pelvic) afterents may differ from somatic (sciatic and pudendal) afferent fibres in their response to injury led to this study of peptide expression in dorsal sacral spinal cord of the cat after pelvic and pudendal nerve transection. Pelvic and pudendal nerve peptide-containing afferents terminate in the same segments of the cat dorsal sacral spinal cord, and changes in their expression of neuropeptides may be more easily studied here than in the periphery. In the first experiment, a group of neonatal Wistar rats (n = 6) were treated with capsaicin (Sigma) systemically two days after birth (50 mg/kg s.c.), which produces a marked selective depletion of unmyelinated afferent fibres [21]; their littermates (n=4) received saline, and served as controls. In the second experiment
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another group of Wistar rats (n=6) were sympathectomised with 6-hydroxydopamine (6-OHDA, Sigma): each rat received 150/zg/g s.c. daily for the first 14 days after birth [12]. The sympthectomised rats showed ptosis, and had a complete loss of catecholamine-staining fibres innervating sciatic nerve vasa nervorum [6]. Control litter mates (n = 4) received saline in the same protocol. In the third experiment, adult mf rats (n = 4) were used, with Sprague-Dawley rats as controls (n =4). All rats were anaesthetized with ether and the right sciatic nerve ligated and transected in the midthigh region. The nerve distal to the ligation was avulsed. The capsaicintreated rats and their controls were operated at the age of 6 weeks, and the sympathectomised rats at the age of two weeks. The rats were sacrificed with an ether overdose two weeks after nerve transection. Peptides were extracted by boiling fresh tissues in 0.5 M acetic acid (1: l 0, w/v). Duplicate aliquots were assayed for galanin, VIP and substance P by sensitive and specific radioimmunoassays, and chromatographic analyses of the immunoreactivities were similar to those previously described [9, 19]. There was a marked increase of galanin content in the terminal 0.5-cm nerve stump when compared to intact nerve, whereas there was a fall of substance P (see Table I for all rat nerve data). Capsaicin pretreatment produced a depletion of substance P in uninjured nerves (P
