Benzodiazepine receptor sites in bovine pineal

[3H]Flunitrazepam (FNZP) binds to a single class of high affinity binding sites in bovine pineal membranes (KD 2.8 nM). FNZP binding increased by 25% after exposure to gamma-aminobutyric acid and exhibits a high degree of specificity for drugs acting on the central type of benzodiazepine receptor. High affinity binding of [3H]ethyl-3-carboline ester to pineal membranes has a KD 0.8 nM and about 60% of the maximal number of FNZP binding sites.