Benzodiazepine receptors in rat brain

HIGH affinity binding of tritium labelled morphine and morphine-like drugs to membranes in brain homogenates 1–3 was a decisive advance in the characterisation of opiate receptors and the discovery of enkephalines and endorphines. We report here experiments which suggest that another important group of psychoactive drugs, the benzodiazepines, bind to specific receptors on the membranes of rat brain cells. This suggests that there may be an unknown endogenous neurotransmitter which is the natural ligand for the benzodiazepine receptor. The binding sites are distributed unevenly through the brain, and displacement potencies of benzodiazepines correlate with pharmacological effects predictive of anxiolytic activity.