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Query: UMLS:C0030193 (pain)
 261,466 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Cryoanalgesia, the technique of freezing peripheral nerves, is used clinically for the treatment of postoperative and chronic pain. Paradoxically, this same technique produces characteristics in a rat model suggestive of neuropathic pain. We have developed a peripheral neuropathy model by freezing the proximal sciatic nerve (sciatic cryoneurolysis, SCN) using a cryoprobe cooled to -60 degrees C in a 30/5/30 sec freeze-thaw-freeze sequence. Each freeze cycle produced a transient ice ball on the surface of the nerve. These studies provide behavioral evidence that SCN is a valid mononeuropathy animal model. All animals demonstrate some degree of autotomy following SCN. The average onset of autotomy occurs 4 days postoperatively and peaks in severity and incidence at 14 days. By examining the latency of responses to a noxious heat stimulus, we have shown there is no direct relationship between an hypoesthetic paw and autotomy, i.e., autotomy did not occur immediately after the freeze lesion when the limb was dysfunctional. Rather, autotomy peaked when sensation was returning to the affected limb. The transient time course of certain behaviors including hypoesthesia and possible return of limb sensation, autotomy, touch-evoked allodynia, foot edema and the presence of spontaneous nociceptive behaviors demonstrate a multiple phase nociceptive process. The temporary nature of these nociceptive behaviors is in sharp contrast to the prolonged bilateral mechanical allodynia evident when these behaviors subside. The surgical anesthetics used during the SCN procedure are shown to variably alter or suppress autotomy following SCN.(ABSTRACT TRUNCATED AT 250 WORDS)
Pain 1994 Jan
PMID:Characterization of a neuropathic pain model: sciatic cryoneurolysis in the rat. 815 45

The putative antinociceptive action of guanethidine and calcitonin systemically injected has been compared in 2 rat models of persistent experimental pain: Freund's adjuvant-induced arthritis (n = 29) and mononeuropathy induced by 4 loose ligatures around the sciatic nerve (n = 24). Guanethidine (30 mg/kg, i.v.) and calcitonin (0.125 mg, s.c.) were injected once a day over 1 week, when hyperalgesia was fully developed. The antinociceptive action was gauged using nociceptive tests based on mechanical or cold stimuli (vocalization threshold to paw pressure and struggle latency to 10 degrees C, respectively), and the score of spontaneous pain-related behavior was measured on the basis of the abnormal hind paw position. No antinociceptive action was observed in calcitonin-compared to saline-injected rats, either in arthritic or neuropathic animals. Guanethidine treatment was ineffective on hyperalgesia exhibited in arthritic rats but was able to reduce reliably and even suppress the abnormal reactions to cold stimulus in neuropathic animals. The lack of hypoalgesic action of calcitonin versus its beneficial action in bone repair, as well as the possible role(s) of the sympathetic system in neuropathic versus arthritic pain and in hyperalgesia versus physical signs of inflammation, are discussed.
Pain 1993 Jan
PMID:Are mechanical and cold allodynia in mononeuropathic and arthritic rats relieved by systemic treatment with calcitonin or guanethidine? 838 11

Adrenal medullary transplants in the spinal subarachnoid space, by providing a continual source of opioid peptides and catecholamines, offer a potentially important adjunct in the management of chronic pain. While previous studies have shown that this approach is effective against high-intensity phasic stimuli, adrenal medullary implants need to be evaluated against long-term and abnormal pain syndromes before transplantation can be used for human chronic pain. Using a recently developed model of painful peripheral neuropathy, the effects of adrenal medullary chromaffin cells transplanted into the subarachnoid space was evaluated. Peripheral mononeuropathy was induced by loosely tying 4 ligatures (4-0 chromic gut) around the right sciatic nerve. This procedure produces various pain symptoms including allodynia, hyperalgesia and dysesthesia. Rats were given either adrenal medullary tissue or control striated muscle transplants. Animals with adrenal medullary tissue transplants showed markedly decreased allodynia to innocuous cold as early as 1 week post-transplantation. In addition, hyperalgesia to a noxious thermal stimulus was eliminated by adrenal medullary, but not control, transplants. Touch-evoked allodynia was only slightly reduced by adrenal medullary transplants. In addition, indicators of spontaneous pain appeared reduced in animals with adrenal medullary transplants. These findings indicate that adrenal medullary transplants may be effective in reducing neuropathic pain.
Pain 1993 Feb
PMID:Reduced pain-related behavior by adrenal medullary transplants in rats with experimental painful peripheral neuropathy. 838 60

The therapeutic effects of dextrorphan and ketamine, two non-competitive N-methyl-D-aspartate (NMDA) receptor antagonists, on neuropathic pain-related behaviors were examined in rats with peripheral mononeuropathy induced by loose ligation of the common sciatic nerve (chronic constrictive injury, CCI). Four daily intrathecal treatments (beginning 1 h after nerve ligation) with dextrorphan or ketamine (12.5-100 nmol) reliably attenuated hyperalgesia to radiant heat and spontaneous pain-related behaviors in CCI rats. Thermal hyperalgesia also was reduced in CCI rats receiving a single intrathecal treatment with either dextrorphan or ketamine (50 and 100 nmol for each compound) on day 3 after nerve ligation when thermal hyperalgesia was well developed. Since both dextrorphan and ketamine are currently utilized in other clinical applications, the results suggest a new therapeutic utility of these 'old' compounds in treatment of neuropathic pain syndromes resulting from peripheral nerve injury.
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PMID:Intrathecal treatment with dextrorphan or ketamine potently reduces pain-related behaviors in a rat model of peripheral mononeuropathy. 838 40

Dextrorphan (DEX), a non-competitive NMDA receptor antagonist, was given intraperitoneally and intrathecally (i.t.) to rats with an experimental painful peripheral mononeuropathy. The neuropathy was created by placing loosely constrictive ligatures around the sciatic nerve, and the pain threshold was studied with the paw-flick method. The effects of DEX on the neuropathic heat-evoked hyperalgesia that follows this nerve injury were determined during the period of peak symptom severity. DEX given i.p. relieved heat-evoked hyperalgesia in a dose-dependent manner without producing motor impairment. The highest doses tested (12.5 and 25 mg/kg) produced a large but incomplete block (about 50%). DEX had no effect on the responsiveness of the paw on the control side. i.t. injection of 20 micrograms DEX completely blocked heat-hyperalgesia when tested 1 h later; again, the effect was achieved without motor impairment and without any change on the control side. These results suggest that DEX may be useful in the treatment of human neuropathic pain.
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PMID:Dextrorphan relieves neuropathic heat-evoked hyperalgesia in the rat. 838 57

Regional changes in brain neural activity were examined in rats with painful peripheral mononeuropathy (chronic constrictive injury, CCI) by using the fully quantitative 14C-2-deoxyglucose (2-DG) autoradiographic technique to measure local glucose utilization rate. CCI rats used in the experiment exhibited demonstrable thermal hyperalgesia and spontaneous pain behaviors 10 d after sciatic nerve ligation when the 2-DG experiment was carried out. In the absence of overt peripheral stimulation, reliable increases in 2-DG metabolic activity were observed in CCI rats as compared to sham-operated rats within extensive brain regions that have been implicated in supraspinal nociceptive processing. These brain regions included cortical somatosensory areas, cingulate cortex, amygdala, ventral posterolateral thalamic nucleus, posterior thalamic nucleus, hypothalamic arcuate nucleus, central gray matter, deep layers of superior colliculus, pontine reticular nuclei, locus coeruleus, parabrachial nucleus, gigantocellular reticular nucleus, and paragigantocellular nucleus. The increase in 2-DG metabolic activity was bilateral in most brain regions of CCI rats. However, somatosensory regions within the thalamus and the cerebral cortex were activated in CCI rats. High levels of 2-DG metabolic activity were observed within the cortical hind limb area, ventral posterolateral thalamic nucleus, and posterior thalamic nucleus contralateral to the ligated sciatic nerve, and these levels were higher than ipsilateral corresponding regions in CCI rats. In addition, patterns of increased neural activity found in the brain of CCI rats showed some similarities and differences to those found in the brain of rats exposed to acute nociception induced by noxious heat or formalin stimulation. Thus, these CCI-induced spontaneous increases in neural activity within extensive brain regions of CCI rats previously implicated in sensory-discriminative and affective-motivational dimensions of pain as well as centrifugal modulation of pain are likely to reflect brain neural processing of spontaneous pain. Implications of increased brain neural activity in mechanisms of neuropathic pain are discussed with emphasis on correlations between spatial patterns of altered brain neural activity and pain-related behaviors in CCI rats and clinical symptoms in neuropathic pain patients.
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PMID:Patterns of increased brain activity indicative of pain in a rat model of peripheral mononeuropathy. 838 24

This study of a mononeuropathy of 1-15 weeks (W) duration was induced in rats by setting 4 loose ligatures around the common sciatic nerve. This chronic lesion, in which the continuity of the nerve was maintained, has been introduced as a model for experimental pain. Quantitative analyses of teased nerve fibres and a morphometric analysis of semi-thin transverse sections, were performed and completed by electron microscopic examination. Morphological changes were observed mainly distal, but also proximal, to the ligatures, indicating significant axonopathy with simultaneous degeneration and regeneration. The lesions were analysed in parallel with the time course of the pain-related behaviours. Both were at their maximum 2 weeks after ligature with progressive recovery beginning between W3 and W4. However, the largest fibres had not totally recovered by W15, contrasting with the disappearance of abnormal nociceptive reactions between W8 and W10. Although the damage to unmyelinated fibres is of importance, the abnormal pain-related behaviours seen in these rats appeared to be closely linked to the presence of both degenerative and regenerative changes in the A delta-range fibres, which did not necessarily correspond to initial A delta fibres.
Pain 1993 May
PMID:Time course of degeneration and regeneration of myelinated nerve fibres following chronic loose ligatures of the rat sciatic nerve: can nerve lesions be linked to the abnormal pain-related behaviours? 839 69

This study evaluated the antinociceptive effects of systemically administered selective opioid agonists of mu (DAMGO), delta (BUBU) and kappa (U 69593) receptors on the vocalization threshold to paw pressure in a rat model of peripheral unilateral mononeuropathy produced by loose ligatures around the common sciatic nerve. DAMGO (0.5-2 mg/kg), BUBU (1.5-6 mg/kg) and U 69593 (0.75-3 mg/kg) injected intravenously (i.v.) produced a potent long-lasting antinociceptive effect on both hind paws. The effects on the lesioned paw were clearly and statistically more potent than for the non-lesioned paw. The selective antinociceptive effect of 2 mg/kg DAMGO, 3 mg/kg BUBU and 1.5 mg/kg U 69593 were completely prevented by prior administration of the appropriate antagonists: 0.1 mg/kg naloxone, 1 mg/kg naltrindole and 0.4 mg/kg MR 2266. The present data clearly show that an acute i.v. injection of these selective opioid agonists induces potent antinociceptive effects in a rat model of peripheral neuropathy. These data are discussed with regard to the classical view that there is opioid resistance in neuropathic pain.
Pain 1993 Jun
PMID:Selective opioid receptor agonists modulate mechanical allodynia in an animal model of neuropathic pain. 839 63

1. Three-dimensional spatial patterns of changes in membrane-bound protein kinase C (PKC) were examined in the lumbar spinal cords (L1-L5) of rats with an experimental painful peripheral mononeuropathy. Painful peripheral mononeuropathy was produced by loosely ligating the rat's common sciatic nerve, resulting in chronic constrictive nerve injury (CCI). Changes in spinal cord membrane-bound PKC distribution were assayed by employing an established quantitative [3H]-phorbol-12,13-dibutyrate ([3H]PDBu) autoradiographic assay, which includes spinal cord sectioning, incubation of spinal cord sections with [3H]PDBu, production of autoradiographs, and computer-assisted image processing. 2. Sciatic nerve ligation induced demonstrable thermal hyperalgesia in response to radiant heat stimulation and spontaneous pain-related behaviors (such as lifting of the nerve-ligated hind paw) in CCI rats 3, 7, and 10 days after unilateral sciatic nerve ligation. 3. Consistent with behavioral changes, CCI rats examined 3 or 10 days after sciatic nerve ligation displayed a three-dimensional pattern of increased membrane-bound PKC in the lumbar spinal cord (L1-L5) strikingly different from that of sham-operated rats: in the dorsoventral dimension, reliable increases in membrane-bound PKC occurred mainly within spinal cord laminae I-IV and V-VI in CCI rats; in the ipsilateral-contralateral dimension, changes in membrane-bound PKC were seen on both sides of the spinal cord in CCI rats with reliably higher levels of membrane-bound PKC on the side ipsilateral than on the side contralateral to sciatic nerve ligation; in the rostrocaudal dimension, increases in membrane-bound PKC in the spinal cord dorsal horns of CCI rats extended from spinal segments L2-L5. 4. Both three-dimensional increases in spinal cord membrane-bound PKC and nociceptive behaviors (thermal hyperalgesia and spontaneous pain behaviors) in CCI rats were reliably reduced after three daily intrathecal treatments with 80 nmol GM1 ganglioside (a glycosphingolipid shown to prevent PKC translocation/activation), the first of which was given 1 h after sciatic nerve ligation. This reduction was seen 24 h but not 7 days after the last GM1 ganglioside treatment. 5. This three-dimensional increase in membrane-bound PKC in the spinal cord dorsal horn of CCI rats displayed high correlations with thermal hyperalgesia and with spontaneous pain-related behaviors in CCI rats observed both 3 and 10 days after sciatic nerve ligation. Similar correlations were observed between decreases in levels of membrane-bound PKC in the spinal cord dorsal horn and the attenuation of nociceptive behaviors in CCI rats after three daily intrathecal treatments with GM1 ganglioside.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Spatial patterns of increased spinal cord membrane-bound protein kinase C and their relation to increases in 14C-2-deoxyglucose metabolic activity in rats with painful peripheral mononeuropathy. 841 Jan 49

Seventeen children with pediatric peroneal mononeuropathies evaluated between 1979 and 1991 are reported. Twelve boys and 5 girls, ranging in age from 1.5 months to 17 years, were referred for footdrop in 16 children (94%) or for lower extremity pain in 1 child (6%). Causes included compression in 10 children (59%), trauma in 3 children (18%), entrapment in 3 children (18%), and indeterminate in 1 child (5%). Based on nerve conduction studies and electromyography, the level of the pediatric peroneal mononeuropathic lesion was the common peroneal nerve in 10 children (59%), the deep peroneal nerve in 2 children (12%), and the superficial peroneal nerve in 1 child (5%). In 4 other children (24%), pediatric peroneal mononeuropathy at the knee was not more precisely identified. Surgical exploration in 3 children with progressive pediatric peroneal mononeuropathy was valuable. Improvement occurred in 13 of 17 children (76%).
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PMID:Pediatric peroneal mononeuropathy: a clinical and electromyographic study. 841 69


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