Differential effects of GABA on peripheral and central type benzodiazepine binding sites in brain

Abstract

The binding of the clinically inactive benzodiazepine [ 3H]RO-5-4864 to brain membranes was investigated. The peripheral type benzodiazepine binding site was demonstrated in brain with an apparent K d of 1.6 nM and a B max of 290 fmol/mg protein. Monophasic Scatchard plots indicate a homogenous population of high affinity sites. The major inhibitory transmitter GABA, has no effect on [ 3H]RO-5-4864 binding to extensively washed brain membranes. The peripheral type benzodiazepine binding site found in brain is therefore not modulated by GABA.