Regional heterogeneity of benzodiazepine binding sites in rat brain

Displacement of [3H]propyl-beta-carboline-3-carboxylate ([3H]PrCC) and [3H]flunitrazepam ([3H]FNM) was studied in rat hippocampus and cerebellum. Diazepam displaced both ligands with equal potency in both regions. Ethyl-beta-carboline-3-carboxylate (beta CCE) and CL 218,872 displaced [3H]PrCC more potently than [3H]FNM and were more potent in the cerebellum than the hippocampus. Beta CCE and CL 218,872 interact more potently with BZ1 than BZ2 sites, while diazepam is equipotent. GABA and chloride ions enhance the potency of diazepam and CL 218,872 but not beta CCE.