Benzodiazepine binding sites in mice forebrain and kidneys: evidence for similar regulation by GABA agonists

Benzodiazepine binding sites in mice forebrain and kidney homogenate were labelled either in vivo (SC injection) or in vitro by 3H-flunitrazepam. The binding in both cases was carried out in vitro in the presence or absence of 10 microM unlabelled flunitrazepam during 60 min at 0 degrees C. When benzodiazepine binding sites were labelled in vivo pretreatment of animals with muscimol (0.75 and 1.5 mg/kg, IP) and fenibut (25 and 100 mg/kg, IP) in a dose-dependent manner facilitated 3H-flunitrazepam binding both in mice forebrain and kidneys. In vitro labelling of benzodiazepine binding sites demonstrated similar to in vivo labelling in forebrain but not in kidneys. The peripheral benzodiazepine binding sites in kidneys are therefore modulated similarly to benzodiazepine binding sites in forebrain by GABA-ergic drugs.