A pharmacological study of Renshaw cell inhibition.

Abstract

In cats anesthetized with pentobarbitone a pharmacological investigation was made of the inhibition of Renshaw cells by dorsal root afferent volleys and ventral root antidromic volleys, and of the inhibition of motoneurons by Renshaw cells. The effects of strychnine, bicuculline and tetanus toxin indicated that both glycine and GABA [.alpha.-aminobytyric acid] operated as inhibitory transmitters released on Renshaw cells by dorsal root volleys. The mutual inhibition of Renshaw cells, and the recurrent inhibition of motoneurons by Renshaw cells, were suppressed by strychnine. Renshaw cells were thus glycinergic inhibitory neurons, a proposal consistent with recent evidence for strychnine-sensitive inhibition of Ia interneurons by Renshaw cells. The pause which followed high frequency synaptic excitation of Renshaw cells was insensitive to strychnine, bicuculline and tetanus toxin, and was considered unlikely to be the consequence of synaptic inhibition.