Pain, 51(1992) 323-327 0 1992 Elsevier Science
323 Publishers
B.V. All rights
reserved
0304-3959/92/$05.00
PAIN 02182
Sympathectomy does not abolish bradykinin-induced cutaneous hyperalgesia in man Richard A. Meyer a,c, Karen D. Davis ‘,l, Srinivasa N. Raja b and James N. Campbell a,c Departments of a Neurosurgery and ‘Anesthesiology, and the ‘Applied Physics Laboratory, Johns Hopkins Unhlersity, Baltimore, MD 21287-7713 (USA) (Received
21 April 1992, revision
received
28 July 1992, accepted
30 July 1992)
Bradykinin is an endogenous peptide that is thought to be a chemical mediator of the hyperalgesia Summary following inflammation. In rat, bradykinin has been postulated to cause hyperalgesia to mechanical stimuli by releasing prostaglandin from sympathetic post-ganglionic terminals. The aim of this study was to determine whether bradykinin-induced cutaneous hyperalgesia in humans requires post-ganglionic sympathetic terminals. In humans, intradermal injection of bradykinin produces dramatic hyperalgesia to heat but not mechanical stimuli. Therefore, we measured the magnitude and duration of pain and hyperalgesia to heat stimuli following intradermal injection of bradykinin into the leg of a woman before and 6 months after an ipsilateral, surgical, lumbar sympathectomy. The pain and hyperalgesia to heat following bradykinin was found to be unaffected by the sympathectomy. These results suggest that the algesic effects of cutaneous bradykinin in human are independent of the sympathetic nervous system. Key words: Sympathetic nervous system; Pain; Injury; Psychophysics; Inflammation;
Introduction Bradykinin is an endogenous peptide that is thought to be a mediator of the hyperalgesia associated with injury. Bradykinin is found in injured tissue and produces pain and hyperalgesia when administered to cutaneous tissue (Armstrong et al. 1953, 1957; Hargreaves et al. 1988; Manning et al. 1991). Bradykinin also activates nociceptors and sensitizes cutaneous nociceptors to heat stimuli (Khan et al. 1992) and noncutaneous nociceptors to mechanical and heat stimuli (Mense and Meyer 1988; Kumazawa et al. 1989; Neugebauer et al. 1989; Grubb et al. 1991). Injection of bradykinin into the paw of rats produces behavioral signs of hyperalgesia to mechanical stimuli (Levine et al. 1986). Since this mechanical hyperalgesia
’ Current Toronto
address: Dept. of MSS lA8, Canada.
Physiology,
University
of
Toronto,
Correspondence to: Richard A. Meyer, Applied Physics Laboratory, Johns Hopkins University, Johns Hopkins Road, Laurel, MD 20723-6099, USA. Tel.: (l-410) 792-6191; FAX: (l-410) 792-6904.
Bradykinin; Hyperalgesia
does not occur in rats who have had a chemical sympathectomy, it has been postulated that the hyperalgesia induced by bradykinin is dependent on the sympathetic nervous system (Levine et al. 1986). We sought to test whether the sympathetic nervous system is involved in bradykinin-induced cutaneous hyperalgesia in man. Intradermal injection of bradykinin in human subjects produces dramatic hyperalgesia to heat but not mechanical stimuli (Manning et al. 1991). Therefore, we tested for the presence of bradykinin-induced heat hyperalgesia in a patient before and after a surgical sympathectomy.
Methods A patient was chosen for this study in whom a surgical sympathkctomy was to be performed on a limb (right leg) which was normal with regard to pain sensations and vasomotor function (see patient description below). The patient participated in test sessions held 2 days before and 6 months after a right-sided, lumbar sympathetic ganglionectomy. As shown in Fig. 1, 4 sites were identified for heat testing: 2 test sites were located on the right leg (sites A and BJ and 2 control sites were located on the right arm (sites C and DJ. On each
324 the test site. Pain ratings to these injections were recorded every 5 set for 2 min. HTSs were then repeated at each site. The locations of the test sites relative to superficial veins were traced on mylar sheets. Six months after the right-sided surgical sympathectomy, the original test sites were located with use of the mylar sheets and the test procedures were repeated at these test sites. In this 2nd series of experiments, bradykinin was also injected at site A after the saline injection and after 1 HTS to confirm that hyperalgesia could be induced at this site. The protocols were approved by the Johns Hopkins University Joint Committee on Clinical Investigation. and inforined consent was obtained from the subject. The subject was free to withdraw from the study at any time.
A.
Right-sided
lumbar /
\
h I\
I
Brodykinin or saline injection
B.
I
i-E-l
ITiE-l
J
I-iEl
I
I -25
Patient description
-20
-15
-10
-5 Time
0 5 (minutes)
10
15
i 20
25
Fig. 1. Experimental paradigm. A: location of test sites. Two sites on the right leg and 2 control sites on the right arm were tested. Bradykinin was injected into sites B and D, and saline was injected into sites A and C. B: heat testing protocol. The heat testing sequence (HTS) consisted of an ascending series of heat stimuli ranging from 39 to 47°C in 1°C increments. The HTS was applied to each site with a IO-min stimulus-free interval. Bradykinin (or saline) was injected at the test site 5 min before a subsequent test series. Testing was performed 2 days before and 6 months after a right-sided lumbar sympathectomy.
test day, heat testing was performed at these sites before and after intradermal injection at the test site of tither bradykinin (10 nmol in 10 ~1 of saline) or saline (10 ~1). A CO, laser thermal stimulator was used to deliver stepped changes in skin temperature to a 7.5mm diameter spot on the skin (Meyer et al. 1976). The heat test sequence (HTS) consisted of an ascending series of 1-set stimuli ranging from 39 to 47°C in 1°C increments. Three seconds before delivery of a stimulus, the skin temperature was raised to a 38°C baseline level. For a given HTS, heat stimuli were alternately presented to 2 test sites (A and B or C and D) every 15 set so that each site was exposed to an ascending series with stimuli presented every 30 sec. The subject was trained to use the technique of magnitude estimation to rate the intensity of the painful stimuli. With this procedure, the subject provided an arbitrary number to the painfulness associated with a 1-set 45°C stimulus presented earlier to a different spot. She then rated the pain to subsequent stimuli in the HTS and to the injections relative to this modulus. A similar procedure has been used by us in the past (Meyer and Campbell 1981; Manning et al. 1991). Two HTSs (with 10 min between sequences) were presented to each test site for baseline heat pain measurements, and then bradykinin (sites B and D) or saline (sites A and C) was injected at
The patient was a l7-year-old white female who was first referred to our Pain Clinic 6 years prior to this study with left knee pain and hyperalgesia of more than a year’s duration. There was no clear history of antecedent trauma. The deep, aching knee pain was also accompanied by shooting pain from the dorsum of the foot to the mid-thigh, particularly during weight bearing. There was associated swelling of the knee and a history of bluish discoloration of the left lower extremity in the absence of trauma. The affected limb was about 1°C cooler than the contralateral normal limb. The patient underwent a series of lumbar sympathetic blocks at a different hospital that provided short-lasting, partial relief ( > 50%) of pain and hyperalgesia. In 1985. she underwent a left lumbar sympathetic ganglionectomy that resulted in near total relief of her hyperalgesia and partial relief of her ongoing pain. During the 3 years following the left-sided sympathectomy. the patient had a gradual recurrence of her left lower extremity pain and hyperalgesia. The possibility of cross-innervation of the left leg from the right lumbar sympathetic nervous system was entertained. Her right leg appeared normal with regard to sensory function (i.e.. normal mechanical sensibility, normal heat pain thresholds and normal response to bradykinin injections) and autonomic function (i.e., skin temperature and blood flow were not abnormal). Two right-sided lumbar sympathetic ganglion blocks resulted in substantial pain relief ( > 70%). Of importance to the present study. a right-sided lumbar sympathetic ganglionectomy was performed that led to near complete relief of her sympathetically maintained pain in her left leg. (An 8-cm length of sympathetic chain was removed along the lumbar spine that included 3 ganglia.) As an indication of the completeness of this sympathectomy, piloerection (i.e.. goose bumps) were only observed proximal to her right knee and her distal leg was warm.
Results The pain evoked by the intradermal injection of bradykinin (10 nmol in 10 ~1 of saline) or saline is shown in Fig. 2. Before the lumbar sympathectomy (Fig. 2A), saline produced only a brief weak pain, whereas bradykinin produced a mild pain that lasted for at least 60 sec. Six months after the lumbar sympathectomy (Fig. 2B), the pain induced by bradykinin injection into the 2 sites in the leg (sites A and B) was not lower than the pain induced by the bradykinin injections before the sympathectomy. Similar pain ratings were obtained for the injections done at the control sites on the arm. The results indicate that an intact sympathetic innervation of the leg is not needed for bradykinin to cause pain.
The pain ratings to the ascending series of heat test stimuli applied to site B on the leg are shown in Fig. 3. At this site, the pain threshold was initially 46°C. Immediately after the bradykinin injection, a pronounced hyperalgesia to heat stimuli was apparent as indicated by a lowering of the pain threshold and an increase in the pain to suprathreshold stimuli. The hyperalgesia to heat after the lumbar sympathectomy (Fig. 3B) was similar to that observed at the same site before the sympathectomy (Fig. 3A). A similar shift in the heat-pain stimulus-response function was observed after the bradykinin injections at the control site on the arm. The results indicate that the sympathetic denervation of the leg did not substantially alter the hyperalgesia to heat stimuli induced by intradermal injection of bradykinin.
6
B. v v
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0,
A. Pre-sympathectomy
- '.,.
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i
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,,
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A)
1
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,
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Stimulus
60
90
120
B. Post-sympathectomy
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0, K .w
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B)
0
BK (Site
A)
0
NS (Site
A)
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‘I Injection
30
Time
60
90
120
(seconds)
Fig. 2. Pain evoked by bradykinin and saline injections. Every 5 set, the subject rated the pain following intradermal injection of bradykinin (BK, 10 nmol in 10 ~1 of saline, 0 and T) or saline (NS, O) relative to the pain of a I-set 45°C stimulus. A: pain ratings obtained 2 days before sympathectomy. B: pain ratings obtained 6 months after the right-sided, lumbar sympathectomy. The magnitude of pain evoked by bradykinin before the sympathectomy was similar to that evoked by bradykinin injected at the same location after the sympathectomy. In addition, the bradykinin injection at the control site (site A) after the saline injection evoked pain of similar magnitude and time course as that observed at site B.
I
i
. 39
30
1
Before BK After BK
01 -
0
0
” 43
,x ”
temperature
” 45
47
(“C)
Fig. 3. Hyperalgesia following bradykinin injection. An ascending series of heat stimuli was used to assess heat pain sensation before ( v 1 and after (v) bradykinin injections to site B on the leg. A: pain ratings obtained 2 days before the sympathectomy. B: pain ratings obtained 6 months after the sympathectomy. Bradykinin-induced hyperalgesia to heat stimuli was characterized by a leftward shift of the stimulus-response function. This hyperalgesia was similar before and after the surgical sympathectomy.
As a single measure of the pain to the HTS, we computed the sum of the pain ratings to each heat test run. As shown in Fig. 4, the total pain ratings increased substantially for the heat run immediately following the bradykinin injection and then returned to baseline 10 min later in the subsequent run. This increase in total response following bradykinin at site B was observed before (Fig. 4A) and after (Fig. 4B) the sympathectomy. Injection of saline did not appreciably alter pain ratings to the HTS.
Discussion A surgical, lumbar sympathectomy had no appreciable effect on the pain and hyperalgesia to heat stimuli evoked by intradermal injection of bradykinin. These results indicate that the pain and hyperalgesia to heat stimuli that occur following bradykinin injection do not require an intact sympathetic nervous system.
326
A. Pre-sympathectomy
20 Q) VI
c 15 i
‘I 0
BK (Site NS (Site
-2
v I
B) A)
-1
I /
1
1
B. Post-sympathectomy I
v
BK (Site
B)
0
BK (Site
A)
0
NS (Site
A)
-2
12
-1
Run
3
number
Fig. 4. Time course of heat hyperalgesia. To evaluate the time course of the changes in heat sensitivity, we computed the total pain ratings of the subject to each heat test run at sites A and B in the right leg. Test runs were repeated every 15 min. A: responses obtained 2 days before the sympathectomy. B: responses obtained 6 months after the sympathectomy. An increase in the total response was observed for the heat test run immediately after the bradykinin injection. Recovery to baseline heat ratings was apparent at the next heat test run after the bradykinin injection, a time course similar to that observed in normal subjects (Manning et al. 1991). No hyperalgesia was observed after the saline injections.
In addition, neurogenic inflammation in rats is not significantly altered following sympathectomy (Donnerer et al. 1991). Another possible explanation is that hyperalgesia to mechanical but not heat stimuli depends on the sympathetic fibers. This possibility could not be tested in humans because hyperalgesia to mechanical stimuli is not observed following an intraderma1 bradykinin injection (Manning et al. 1991 I. Another possibility is that the surgical sympathectomy was incomplete and that the surviving sympathetic fibers account for bradykinin’s effect. However, the observation that the hyperalgesia to heat before and after sympathectomy was almost identical would require that the few sympathetic terminals which survived the surgical sympathectomy have the same capacity to produce hyperalgesia as the intact system. It should be noted that chemical sympathectomies in rats do not lead to complete depletion of noradrenaline in the skin (Donnerer et al. 1991). Levine et al. (1986) postulate that bradykinin causes prostaglandin to be released from the post-ganglionic sympathetic terminals. The prostaglandin then sensitizes the primary nociceptive afferents leading to hyperalgesia. Indeed, prostaglandin administration causes hyperalgesia to mechanical stimuli (Raja et al. unpublished observations), sensitization of nociceptors (Handwerker 1976; Pateromichelakis and Rood 1982; Schaible and Schmidt 1986; Martin et al. 1987; Raja et al. 1990) and an enhanced response to bradykinin (Handwerker 1976; Neugebauer et al. 1989; Grubb et al. 1991). The lack of hyperalgesia to mechanical stimuli following bradykinin injections in man (Manning et al. 19911 suggests that prostaglandins are not released by the post-ganglionic sympathetic terminals following bradykinin injection.
Acknowledgements
The fact that the pain induced by bradykinin is independent of the sympathetic system is not surprising since bradykinin has been shown to activate isolated dorsal root ganglion cells in culture (e.g., Burgess et al. 1989). However, our finding that the cutaneous hyperalgesia to heat induced by bradykinin is also independent of the sympathetic nervous system is in contrast to the observations of Levine et al. (1986) that bradykinin-induced hyperalgesia to mechanical stimuli is eliminated in rats following a chemical sympathectomy. One possible explanation of this discrepancy is the difference in species. However, Koltzenburg et al. (1992) demonstrated that bradykinin-induced sensitization of nociceptors to heat stimuli was similar for intact and surgically sympathectomized rats (bradykinin does not sensitize cutaneous C-fiber nociceptors to mechanical stimuli (Khan et al. 1992; Koltzenburg et al. 19921).
We wish to thank Ms. Jennifer L. Turnquist and Mr. Timothy V. Hartke for their technical assistance during the course of these studies. This research was supported by NIH grants NS-14447 and NS-26363.
References Armstrong, D., Dry, R.M.L., Keele. CA. and Markham, J.W.. Observations on chemical excitants of cutaneous pain in man, J. Physiol. (Land.). 120 (1953) 326-351. Armstrong. D., Jepson, J.B., Keele. C.A. and Stewart. J.W.. Painproducing substances in human inflammatory exudates and plasma, J. Physiol. (Land.), 135 (1957) 350-370. Burgess, G.M., Mullaney. I.. McNeill, M.. Dunn, P.M. and Rang, H.P., Second messengers involved in the mechanism of action of bradykinin in sensory neurons in culture, J. Neurosci., 9 (1989) 3314-3325.
327 Donnerer, J.. Amann, R. and Lembeck, F., Neurogenic and non-neurogenic inflammation in the rat paw following chemical sympathectomy, Neuroscience, 45 (19911 761-765. Grubb, B.D., Birrell, G.J.. McQueen, D.S. and Iggo, A., The role of PGEz in the sensitization of mechanoreceptors in normal and inflamed ankle joints of the rat, Exp. Brain Res., 84 (19911 383-392. Handwerker, H.O., Influences of algogenic substances and prostaglandins on the discharge of unmyelinated cutaneous nerve fibers identified as nociceptors. In: J.J. Bonica and D. Albe-Fessard (Eds.), Advances in Pain Research and Therapy, Vol. 1, Raven Press, New York, 1976, pp. 41-45. Hargreaves, K.M., Troullos, ES., Dionne, R.A., Schmidt, E.A.. Schafer, S.C. and Joris. J.L., Bradykinin is increased during acute and chronic inflammation: therapeutic implications, Clin. Pharmacol. Ther., 44 (1988) 613-621. Khan, A.A., Raja, S.N., Manning, D.C., Campbell, J.N. and Meyer, R.A., The effects of bradykinin and sequence-related analogs on the response properties of cutaneous nociceptors in monkey, Somatosens. Motor Res., 9 (1992197-106. Koltzenburg, M.. Kress. M. and Reeh, P.W., The nociceptor sensitization by bradykinin does not depend on sympathetic neurons, Neurosci.. 46 (1992) 465-473. Kumazawa, T., Mizumura, K., Minagawa. M. and Tsujii, Y., Sensitizing effects of bradykinin on the heat responses of the visceral nociceptor, J. Neurophysiol., 66 (19911 1819-1824. Levine, J.D.. Taiwo, Y.O., Collins, S.D. and Tam. J.K., Noradrenaline hyperalgesia is mediated through interaction with sympathetic postganglionic neurone terminals rather than activation of primary afferent nociceptors, Nature, 323 (1986) 1.58160.
Manning,D.C., Raja, S.N., Meyer, R.A. and Campbell, J.N., Pain and hyperalgesia after intradermal injection of bradykinin in humans, Clin. Pharmacol. Ther., 50 (19911 721-729. Martin, H.A., Bausbaum, A.I., Kwait, A.C., Goetzl, E.J. and Levine, J.D., Leukotriene and prostaglandin sensitization of cutaneous high threshold C and A-delta mechanoreceptors in the hairy skin of rat hindlimbs, Neuroscience 22 (1987) 651-659. Mense, S. and Meyer, H., Bradykinin-induced modulation of the response behaviour of different types of feline group III and IV muscle receptors, J. Physiol. (Lond.1, 398 (1988) 49-63. Meyer, R.A. and Campbell, J.N.. Myelinated nociceptive afferents account for the hyperalgesia that follows a burn to the hand, Science, 213 (1981) 1527-1529. Meyer, R.A., Walker, R.E. and Mountcastle, V.B., A laser stimulator for the study of cutaneous thermal and pain sensations, IEEE Biomed. Eng., 23 (19761 54-60. Neugebauer, V., Schaible, H.-G. and Schmidt, R.F., Sensitization of articular afferents to mechanical stimuli by bradykinin, Pflugers Arch., 415 (19891330-335. Pateromichelakis, S. and Rood, J.P., Prostaglandin E,-induced sensitization of A6 moderate pressure mechanoreceptors, Brain Res., 232 (1982) 89-96. Raja. S.N., Mitzel, E.L. and Campbell, J.N., Prostaglandin E, sensitizes cutaneous nociceptors in monkey, Sot. Neurosci. Abst., 16 (19901415. Schaible, H.-G. and Schmidt, R.F.. Discharge characteristics of receptors with fine afferents from normal and inflamed joints, influence of analgesics and prostaglandins. Agents Actions, Suppl. 19 (1986199-117.
323 Publishers
B.V. All rights
reserved
0304-3959/92/$05.00
PAIN 02182
Sympathectomy does not abolish bradykinin-induced cutaneous hyperalgesia in man Richard A. Meyer a,c, Karen D. Davis ‘,l, Srinivasa N. Raja b and James N. Campbell a,c Departments of a Neurosurgery and ‘Anesthesiology, and the ‘Applied Physics Laboratory, Johns Hopkins Unhlersity, Baltimore, MD 21287-7713 (USA) (Received
21 April 1992, revision
received
28 July 1992, accepted
30 July 1992)
Bradykinin is an endogenous peptide that is thought to be a chemical mediator of the hyperalgesia Summary following inflammation. In rat, bradykinin has been postulated to cause hyperalgesia to mechanical stimuli by releasing prostaglandin from sympathetic post-ganglionic terminals. The aim of this study was to determine whether bradykinin-induced cutaneous hyperalgesia in humans requires post-ganglionic sympathetic terminals. In humans, intradermal injection of bradykinin produces dramatic hyperalgesia to heat but not mechanical stimuli. Therefore, we measured the magnitude and duration of pain and hyperalgesia to heat stimuli following intradermal injection of bradykinin into the leg of a woman before and 6 months after an ipsilateral, surgical, lumbar sympathectomy. The pain and hyperalgesia to heat following bradykinin was found to be unaffected by the sympathectomy. These results suggest that the algesic effects of cutaneous bradykinin in human are independent of the sympathetic nervous system. Key words: Sympathetic nervous system; Pain; Injury; Psychophysics; Inflammation;
Introduction Bradykinin is an endogenous peptide that is thought to be a mediator of the hyperalgesia associated with injury. Bradykinin is found in injured tissue and produces pain and hyperalgesia when administered to cutaneous tissue (Armstrong et al. 1953, 1957; Hargreaves et al. 1988; Manning et al. 1991). Bradykinin also activates nociceptors and sensitizes cutaneous nociceptors to heat stimuli (Khan et al. 1992) and noncutaneous nociceptors to mechanical and heat stimuli (Mense and Meyer 1988; Kumazawa et al. 1989; Neugebauer et al. 1989; Grubb et al. 1991). Injection of bradykinin into the paw of rats produces behavioral signs of hyperalgesia to mechanical stimuli (Levine et al. 1986). Since this mechanical hyperalgesia
’ Current Toronto
address: Dept. of MSS lA8, Canada.
Physiology,
University
of
Toronto,
Correspondence to: Richard A. Meyer, Applied Physics Laboratory, Johns Hopkins University, Johns Hopkins Road, Laurel, MD 20723-6099, USA. Tel.: (l-410) 792-6191; FAX: (l-410) 792-6904.
Bradykinin; Hyperalgesia
does not occur in rats who have had a chemical sympathectomy, it has been postulated that the hyperalgesia induced by bradykinin is dependent on the sympathetic nervous system (Levine et al. 1986). We sought to test whether the sympathetic nervous system is involved in bradykinin-induced cutaneous hyperalgesia in man. Intradermal injection of bradykinin in human subjects produces dramatic hyperalgesia to heat but not mechanical stimuli (Manning et al. 1991). Therefore, we tested for the presence of bradykinin-induced heat hyperalgesia in a patient before and after a surgical sympathectomy.
Methods A patient was chosen for this study in whom a surgical sympathkctomy was to be performed on a limb (right leg) which was normal with regard to pain sensations and vasomotor function (see patient description below). The patient participated in test sessions held 2 days before and 6 months after a right-sided, lumbar sympathetic ganglionectomy. As shown in Fig. 1, 4 sites were identified for heat testing: 2 test sites were located on the right leg (sites A and BJ and 2 control sites were located on the right arm (sites C and DJ. On each
324 the test site. Pain ratings to these injections were recorded every 5 set for 2 min. HTSs were then repeated at each site. The locations of the test sites relative to superficial veins were traced on mylar sheets. Six months after the right-sided surgical sympathectomy, the original test sites were located with use of the mylar sheets and the test procedures were repeated at these test sites. In this 2nd series of experiments, bradykinin was also injected at site A after the saline injection and after 1 HTS to confirm that hyperalgesia could be induced at this site. The protocols were approved by the Johns Hopkins University Joint Committee on Clinical Investigation. and inforined consent was obtained from the subject. The subject was free to withdraw from the study at any time.
A.
Right-sided
lumbar /
\
h I\
I
Brodykinin or saline injection
B.
I
i-E-l
ITiE-l
J
I-iEl
I
I -25
Patient description
-20
-15
-10
-5 Time
0 5 (minutes)
10
15
i 20
25
Fig. 1. Experimental paradigm. A: location of test sites. Two sites on the right leg and 2 control sites on the right arm were tested. Bradykinin was injected into sites B and D, and saline was injected into sites A and C. B: heat testing protocol. The heat testing sequence (HTS) consisted of an ascending series of heat stimuli ranging from 39 to 47°C in 1°C increments. The HTS was applied to each site with a IO-min stimulus-free interval. Bradykinin (or saline) was injected at the test site 5 min before a subsequent test series. Testing was performed 2 days before and 6 months after a right-sided lumbar sympathectomy.
test day, heat testing was performed at these sites before and after intradermal injection at the test site of tither bradykinin (10 nmol in 10 ~1 of saline) or saline (10 ~1). A CO, laser thermal stimulator was used to deliver stepped changes in skin temperature to a 7.5mm diameter spot on the skin (Meyer et al. 1976). The heat test sequence (HTS) consisted of an ascending series of 1-set stimuli ranging from 39 to 47°C in 1°C increments. Three seconds before delivery of a stimulus, the skin temperature was raised to a 38°C baseline level. For a given HTS, heat stimuli were alternately presented to 2 test sites (A and B or C and D) every 15 set so that each site was exposed to an ascending series with stimuli presented every 30 sec. The subject was trained to use the technique of magnitude estimation to rate the intensity of the painful stimuli. With this procedure, the subject provided an arbitrary number to the painfulness associated with a 1-set 45°C stimulus presented earlier to a different spot. She then rated the pain to subsequent stimuli in the HTS and to the injections relative to this modulus. A similar procedure has been used by us in the past (Meyer and Campbell 1981; Manning et al. 1991). Two HTSs (with 10 min between sequences) were presented to each test site for baseline heat pain measurements, and then bradykinin (sites B and D) or saline (sites A and C) was injected at
The patient was a l7-year-old white female who was first referred to our Pain Clinic 6 years prior to this study with left knee pain and hyperalgesia of more than a year’s duration. There was no clear history of antecedent trauma. The deep, aching knee pain was also accompanied by shooting pain from the dorsum of the foot to the mid-thigh, particularly during weight bearing. There was associated swelling of the knee and a history of bluish discoloration of the left lower extremity in the absence of trauma. The affected limb was about 1°C cooler than the contralateral normal limb. The patient underwent a series of lumbar sympathetic blocks at a different hospital that provided short-lasting, partial relief ( > 50%) of pain and hyperalgesia. In 1985. she underwent a left lumbar sympathetic ganglionectomy that resulted in near total relief of her hyperalgesia and partial relief of her ongoing pain. During the 3 years following the left-sided sympathectomy. the patient had a gradual recurrence of her left lower extremity pain and hyperalgesia. The possibility of cross-innervation of the left leg from the right lumbar sympathetic nervous system was entertained. Her right leg appeared normal with regard to sensory function (i.e.. normal mechanical sensibility, normal heat pain thresholds and normal response to bradykinin injections) and autonomic function (i.e., skin temperature and blood flow were not abnormal). Two right-sided lumbar sympathetic ganglion blocks resulted in substantial pain relief ( > 70%). Of importance to the present study. a right-sided lumbar sympathetic ganglionectomy was performed that led to near complete relief of her sympathetically maintained pain in her left leg. (An 8-cm length of sympathetic chain was removed along the lumbar spine that included 3 ganglia.) As an indication of the completeness of this sympathectomy, piloerection (i.e.. goose bumps) were only observed proximal to her right knee and her distal leg was warm.
Results The pain evoked by the intradermal injection of bradykinin (10 nmol in 10 ~1 of saline) or saline is shown in Fig. 2. Before the lumbar sympathectomy (Fig. 2A), saline produced only a brief weak pain, whereas bradykinin produced a mild pain that lasted for at least 60 sec. Six months after the lumbar sympathectomy (Fig. 2B), the pain induced by bradykinin injection into the 2 sites in the leg (sites A and B) was not lower than the pain induced by the bradykinin injections before the sympathectomy. Similar pain ratings were obtained for the injections done at the control sites on the arm. The results indicate that an intact sympathetic innervation of the leg is not needed for bradykinin to cause pain.
The pain ratings to the ascending series of heat test stimuli applied to site B on the leg are shown in Fig. 3. At this site, the pain threshold was initially 46°C. Immediately after the bradykinin injection, a pronounced hyperalgesia to heat stimuli was apparent as indicated by a lowering of the pain threshold and an increase in the pain to suprathreshold stimuli. The hyperalgesia to heat after the lumbar sympathectomy (Fig. 3B) was similar to that observed at the same site before the sympathectomy (Fig. 3A). A similar shift in the heat-pain stimulus-response function was observed after the bradykinin injections at the control site on the arm. The results indicate that the sympathetic denervation of the leg did not substantially alter the hyperalgesia to heat stimuli induced by intradermal injection of bradykinin.
6
B. v v
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0,
A. Pre-sympathectomy
- '.,.
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” 41
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60
90
120
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0, K .w
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0
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Time
60
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120
(seconds)
Fig. 2. Pain evoked by bradykinin and saline injections. Every 5 set, the subject rated the pain following intradermal injection of bradykinin (BK, 10 nmol in 10 ~1 of saline, 0 and T) or saline (NS, O) relative to the pain of a I-set 45°C stimulus. A: pain ratings obtained 2 days before sympathectomy. B: pain ratings obtained 6 months after the right-sided, lumbar sympathectomy. The magnitude of pain evoked by bradykinin before the sympathectomy was similar to that evoked by bradykinin injected at the same location after the sympathectomy. In addition, the bradykinin injection at the control site (site A) after the saline injection evoked pain of similar magnitude and time course as that observed at site B.
I
i
. 39
30
1
Before BK After BK
01 -
0
0
” 43
,x ”
temperature
” 45
47
(“C)
Fig. 3. Hyperalgesia following bradykinin injection. An ascending series of heat stimuli was used to assess heat pain sensation before ( v 1 and after (v) bradykinin injections to site B on the leg. A: pain ratings obtained 2 days before the sympathectomy. B: pain ratings obtained 6 months after the sympathectomy. Bradykinin-induced hyperalgesia to heat stimuli was characterized by a leftward shift of the stimulus-response function. This hyperalgesia was similar before and after the surgical sympathectomy.
As a single measure of the pain to the HTS, we computed the sum of the pain ratings to each heat test run. As shown in Fig. 4, the total pain ratings increased substantially for the heat run immediately following the bradykinin injection and then returned to baseline 10 min later in the subsequent run. This increase in total response following bradykinin at site B was observed before (Fig. 4A) and after (Fig. 4B) the sympathectomy. Injection of saline did not appreciably alter pain ratings to the HTS.
Discussion A surgical, lumbar sympathectomy had no appreciable effect on the pain and hyperalgesia to heat stimuli evoked by intradermal injection of bradykinin. These results indicate that the pain and hyperalgesia to heat stimuli that occur following bradykinin injection do not require an intact sympathetic nervous system.
326
A. Pre-sympathectomy
20 Q) VI
c 15 i
‘I 0
BK (Site NS (Site
-2
v I
B) A)
-1
I /
1
1
B. Post-sympathectomy I
v
BK (Site
B)
0
BK (Site
A)
0
NS (Site
A)
-2
12
-1
Run
3
number
Fig. 4. Time course of heat hyperalgesia. To evaluate the time course of the changes in heat sensitivity, we computed the total pain ratings of the subject to each heat test run at sites A and B in the right leg. Test runs were repeated every 15 min. A: responses obtained 2 days before the sympathectomy. B: responses obtained 6 months after the sympathectomy. An increase in the total response was observed for the heat test run immediately after the bradykinin injection. Recovery to baseline heat ratings was apparent at the next heat test run after the bradykinin injection, a time course similar to that observed in normal subjects (Manning et al. 1991). No hyperalgesia was observed after the saline injections.
In addition, neurogenic inflammation in rats is not significantly altered following sympathectomy (Donnerer et al. 1991). Another possible explanation is that hyperalgesia to mechanical but not heat stimuli depends on the sympathetic fibers. This possibility could not be tested in humans because hyperalgesia to mechanical stimuli is not observed following an intraderma1 bradykinin injection (Manning et al. 1991 I. Another possibility is that the surgical sympathectomy was incomplete and that the surviving sympathetic fibers account for bradykinin’s effect. However, the observation that the hyperalgesia to heat before and after sympathectomy was almost identical would require that the few sympathetic terminals which survived the surgical sympathectomy have the same capacity to produce hyperalgesia as the intact system. It should be noted that chemical sympathectomies in rats do not lead to complete depletion of noradrenaline in the skin (Donnerer et al. 1991). Levine et al. (1986) postulate that bradykinin causes prostaglandin to be released from the post-ganglionic sympathetic terminals. The prostaglandin then sensitizes the primary nociceptive afferents leading to hyperalgesia. Indeed, prostaglandin administration causes hyperalgesia to mechanical stimuli (Raja et al. unpublished observations), sensitization of nociceptors (Handwerker 1976; Pateromichelakis and Rood 1982; Schaible and Schmidt 1986; Martin et al. 1987; Raja et al. 1990) and an enhanced response to bradykinin (Handwerker 1976; Neugebauer et al. 1989; Grubb et al. 1991). The lack of hyperalgesia to mechanical stimuli following bradykinin injections in man (Manning et al. 19911 suggests that prostaglandins are not released by the post-ganglionic sympathetic terminals following bradykinin injection.
Acknowledgements
The fact that the pain induced by bradykinin is independent of the sympathetic system is not surprising since bradykinin has been shown to activate isolated dorsal root ganglion cells in culture (e.g., Burgess et al. 1989). However, our finding that the cutaneous hyperalgesia to heat induced by bradykinin is also independent of the sympathetic nervous system is in contrast to the observations of Levine et al. (1986) that bradykinin-induced hyperalgesia to mechanical stimuli is eliminated in rats following a chemical sympathectomy. One possible explanation of this discrepancy is the difference in species. However, Koltzenburg et al. (1992) demonstrated that bradykinin-induced sensitization of nociceptors to heat stimuli was similar for intact and surgically sympathectomized rats (bradykinin does not sensitize cutaneous C-fiber nociceptors to mechanical stimuli (Khan et al. 1992; Koltzenburg et al. 19921).
We wish to thank Ms. Jennifer L. Turnquist and Mr. Timothy V. Hartke for their technical assistance during the course of these studies. This research was supported by NIH grants NS-14447 and NS-26363.
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