INHIBITION OF HIPPOCAMPAL ACETYLCHOLINE-RELEASE BY BENZODIAZEPINES - ANTAGONISM BY FLUMAZENIL

Diazepam (2.5-10 mg/kg i.p.) and midazolam (2.5-10 mg/kg i.p.) decreas ed acetylcholine release in the hippocampus of freely moving rats. Thi s effect was antagonized by pretreatment with flumazenil (1 mg/kg i.p. ). These results show that activation of benzodiazepine receptors redu ces the in vivo release of acetylcholine in the hippocampus, suggestin g that the septo-hippocampal cholinergic system, which has a major rol e in the regulation of cognitive functions, is under inhibitory contro l exerted by gamma-aminobutyrate (GABA) neurons.