title: Effects of capsaicin applied locally to adult peripheral nerve. I. Physiology of peripheral nerve and spinal cord.
abstract: (1) Systemic capsaicin treatment of neonatal and adult rats is known to affect unmyelinated afferents. However, the systemic route of administration presents several disadvantages and in order to overcome these a method was explored where a single nerve in adult rats was locally treated. (2) Sciatic nerves were exposed and a 10 mm length was soaked for 15 min in 1.5% capsaicin in vehicle or in the vehicle alone (10% Tween 80, 10% ethyl alcohol in saline). (3) Both the capsaicin solution and the vehicle caused acute block of the C compound action potential while in contact with the nerve. Removal of the solutions, however, resulted in substantial recovery of C fibre conduction. The A fibre volley was totally unaffected. (4) 13-21 days after treatment, the size of the myelinated and unmyelinated volleys evoked by maximal stimulation of the capsaicin treated nerve were unchanged but there was a 20% decrease of conduction velocity in the C fibres. (5) The ability of the maximal C volley from the treated nerve to excite cells in the spinal cord was substantially decreased (by 50%) 13-21 days after local capsaicin.
mesh_terms: D000818:Animals; D002211:Capsaicin / Q000008:administration & dosage / Q000494:pharmacology*; D005071:Evoked Potentials / Q000187:drug effects; D005231:Fatty Acids, Unsaturated / Q000494:pharmacology*; D009412:Nerve Fibers / Q000187:drug effects / Q000502:physiology; D009431:Neural Conduction / Q000187:drug effects; D010525:Peripheral Nerves / Q000187:drug effects* / Q000502:physiology; D051381:Rats; D011919:Rats, Inbred Strains; D012584:Sciatic Nerve / Q000187:drug effects / Q000502:physiology; D013116:Spinal Cord / Q000187:drug effects* / Q000502:physiology
chemical_list: D005231:Fatty Acids, Unsaturated; D002211:Capsaicin