Neonatal capsaicin treatment prevents the development of the thermal hyperalgesia produced in a model of neuropathic pain in the rat.
Pain
; 51(3): 317-321, 1992 Dec.
Article
em En
| MEDLINE
| ID: mdl-1283462
ABSTRACT
Loose ligation of the sciatic nerve with 4-0 chromic gut sutures in rats produces behavioral evidence of neuropathic pain. In the present experiments we examined the involvement of capsaicin-sensitive afferents in mediating the thermal hyperalgesia produced by this model. Male Sprague-Dawley rats, treated as neonates (within 48 h of birth) with capsaicin (50 mg/kg, s.c.) or vehicle, were used at 16-18 weeks of age. Chromic gut sutures (4-0) were tied around the left sciatic nerve and withdrawal latencies of both hind paws to radiant heat were determined on postoperative days 3, 5, 10 and 20. Whereas there was a pronounced thermal hyperalgesia which lasted for up to 20 days in vehicle-treated rats, there was no evidence of thermal hyperalgesia in capsaicin-treated rats. There was no difference in baseline (pre-surgery) withdrawal latencies between the two groups. Radioimmunoassay revealed that there was a significant depletion of substance P (43.8%) and calcitonin-gene-related peptide (72.6%) in the lumbar spinal cord of neonatal capsaicin-treated rats compared to vehicle-treated rats. These results demonstrate that the chromic gut-induced thermal hyperalgesia is mediated by capsaicin-sensitive afferents and suggest that central mechanisms which process and control the reflex response to heat are different than mechanisms involved in thermal hyperalgesia.
Texto completo:
1
Base de dados:
MEDLINE
Assunto principal:
Dor
/
Capsaicina
/
Animais Recém-Nascidos
/
Doenças do Sistema Nervoso
Tipo de estudo:
Etiology_studies
Limite:
Animals
Idioma:
En
Ano de publicação:
1992
Tipo de documento:
Article