Intrathecal apamin selectively facilitates activity in ascending axons of rat spinal cord evoked by stimulation of afferent C fibers in sural nerve.
Intrathecally administered apamin was tested for its effect on activity in ascending axons of the spinal cord using decerebrate rats with low spinal cord transection. Afferent A beta, A delta or C fibers were stimulated in the sural nerve, and the response evoked in ascending axons was recorded below the transection. Apamin (5 ng) produced an increase in C fiber-evoked activity which developed about 30 min after injection and persisted for more than 60 min after injection. Apamin (5, 20 and 50 ng) did not change the activity in ascending axons which responded only to stimulation of afferent A beta and A delta fibers. The results indicate that apamin facilitates synaptic transmission from high-threshold afferent C fibers to secondary neurons.
D000344:Afferent Pathways / Q000502:physiology*; D000818:Animals; D001030:Apamin / Q000008:administration & dosage / Q000494:pharmacology*; D001369:Axons / Q000187:drug effects / Q000502:physiology*; D001514:Bee Venoms / Q000494:pharmacology*; D005071:Evoked Potentials / Q000187:drug effects; D005260:Female; D007278:Injections, Spinal; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D013116:Spinal Cord / Q000187:drug effects / Q000502:physiology*; D013127:Spinal Nerves / Q000502:physiology*; D013497:Sural Nerve / Q000502:physiology*
D001514:Bee Venoms; D001030:Apamin