BICUCULLINE AND SPINAL INHIBITION PRODUCED BY DORSAL COLUMN STIMULATION IN THE CAT

In barbiturate anesthetized cats, dorsal column stimulation inhibited ascending volleys recorded in the antero-lateral spinal fasciculus from electrical stimulation of the contralateral tibial nerve and the excitation of neurons of the dorsal horn by noxious heating of the skin. The inhibition was non-selective. I.v. bicuculline (0.2-0.6 mg/kg) reduced dorsal column induced inhibition of ascending volleys. Bicuculline but not strychnine, administered electrophoretically from micropipettes, reduced dorsal column induced inhibition of the excitation of dorsal horn neurons by noxious heat. The inhibition studied was apparently produced by release of GABA. This amino acid may play a role in the clinical suppression of pain produced by dorsal column stimulation.