Abstract

The order of potency of several γ-aminobutyric acid (GABA) receptor agonists in inhibiting stimulated GABA release from rat cortical synaptosomes was the same as that for inhibiting specific [³H]GABA binding in synaptic plasma membranes. This finding suggests that GABA autoreceptors are identical pharmacologically with sites labeled with [³H]GABA in binding studies. There was a good correlation between receptor occupancy and inhibition of release, suggesting a direct coupling of the autoreceptors to the effector mechanism and the absence of "spare" autoreceptors.