Autotomy in rats after peripheral nerve section: lack of effect of topical nerve or neonatal capsaicin treatment.
The influence of capsaicin on autotomy was studied in adult rats in which the sciatic and saphenous nerves were sectioned. Capsaicin was administered subcutaneously to neonatal rats or applied topically to the sciatic and saphenous nerves in adult animals. Quantification of neurogenic plasma extravasation in skin areas subserved by these nerves and of the number of small type B neurones in lumbar sensory ganglia were used to confirm the effectiveness of capsaicin-induced lesions of unmyelinated sensory nerves. Neonatal capsaicin treatment significantly reduced neuronal numbers in ganglia and, compared to control responses, plasma extravasation was nearly abolished after both neonatal and peripheral nerve treatment with capsaicin. Despite these deficits in sensory neurones function, no differences in any parameters of autotomy were observed between animals receiving both capsaicin treatment and nerve section and those given nerve section alone. Animals in both control and experimental groups exhibited high autotomy scores. These results suggest that capsaicin-sensitive primary sensory neurones do not have a significant role in precipitating autotomy characterized by high incidence and severity.
D000287:Administration, Topical; D000818:Animals; D002211:Capsaicin / Q000494:pharmacology*; D005727:Ganglia, Spinal / Q000187:drug effects; D006614:Hindlimb / Q000294:innervation*; D007279:Injections, Subcutaneous; D008297:Male; D009412:Nerve Fibers / Q000187:drug effects; D009474:Neurons / Q000187:drug effects; D009619:Nociceptors / Q000187:drug effects; D059348:Peripheral Nerve Injuries; D010525:Peripheral Nerves / Q000187:drug effects; D051381:Rats; D011919:Rats, Inbred Strains; D012584:Sciatic Nerve / Q000187:drug effects / Q000293:injuries; D012684:Sensory Thresholds / Q000187:drug effects; D009435:Synaptic Transmission / Q000187:drug effects*
D002211:Capsaicin