Altered excitability of afferent C-fibres of the rat distal to a nerve site exposed to capsaicin.
Excitability of afferent C-fibres in saphenous and coccygeal nerves of rats was studied distal to a nerve site treated with 1% capsaicin for half an hour one day before. This treatment induced the following changes. (a) Fewer C-fibres than in control nerves were excited by natural skin stimulation among those driven by electrical nerve stimulation. Comparison of compound action potentials derived from capsaicin-treated and from untreated contralateral coccygeal nerves indicated that the total number of excitable C-fibres was also diminished. (b) Whereas in a normal rat nerve virtually all unmyelinated nociceptors responding to heat stimulation are also driven by strong mechanical stimuli (MH-nociceptors, polymodal nociceptors), most of them were found to respond only to heat stimulation after local capsaicon treatment of the nerve.
D000200:Action Potentials / Q000187:drug effects; D000344:Afferent Pathways / Q000187:drug effects; D000818:Animals; D001370:Axonal Transport / Q000187:drug effects; D002211:Capsaicin / Q000494:pharmacology*; D004558:Electric Stimulation; D006358:Hot Temperature; D009412:Nerve Fibers / Q000187:drug effects*; D018377:Neurotransmitter Agents / Q000378:metabolism; D009619:Nociceptors / Q000187:drug effects*; D010812:Physical Stimulation; D051381:Rats; D011919:Rats, Inbred Strains; D012445:Sacrococcygeal Region / Q000294:innervation; D012867:Skin / Q000294:innervation
D018377:Neurotransmitter Agents; D002211:Capsaicin