The benzodiazepine receptor in normal and pathological human brain.

Benzodiazepines bind with high affinity to a specific benzodiazepine receptor, which occurs exclusively in the central nervous system. The affinity of various benzodiazepines to the receptor closely parallels their pharmacological and therapeutic potency. Binding to the receptor is stereospecific. The receptor is mainly localized in the synaptic membrane fraction and has its highest density in cortical areas of the brain. In Huntington's chorea a decrease in benzodiazepine receptor binding is found in caudate nucleus and putamen, which, at least in putamen, is due to a loss of benzodiazepine receptors apparently located on GABA neurones, which degenerate in Huntington's chorea. The loss of benzodiazepine receptors might explain why the ameliorative effects of benzodiazepines in the early stages of the disease are not sustained in the later stages.