A GABA-mediated inhibition of neurones in the nucleus tractus solitarius of the cat that respond to electrical stimulation of the carotid sinus nerve.

Extracellular recordings were made from 39 single neurones in the nucleus tractus solitarius which were activated following electrical stimulation of the carotid sinus nerve in chloralose anaesthetised cats. Iontophoretic application of GABA abolished or markedly reduced the evoked activity of all neurones. The inhibitory effect of GABA could be antagonised by the simultaneous iontophoretic application of bicuculline. The iontophoretic application of bicuculline alone resulted in a significant increase in the evoked activity of eleven out of seventeen neurones. These results support the notion that a GABAergic inhibitory system, with the potential to modulate sinus nerve reflexes, acts within the nucleus tractus solitarius.