Effects of Chronic Chlorpromazine Treatment on Peripheral Benzodiazepine Binding Sites in Heart, Kidney, and Cerebral Cortex of Rats

Abstract: Daily intraperitoneal administration to rats of 5 mg/kg of chlorpromazine (CPZ) for 21 days induced a significant up‐regulation (51%) of peripheral benzodiazepine binding sites (PBSs) in cerebral cortex and a down‐regulation of PBSs in the heart (25%) and kidney (14%), whereas no alteration in [³H]flunitrazepam binding in cerebral cortex was observed. [³H]PK 11195 binding to cerebral cortex returned to normal following 5 days of CPZ withdrawal, whereas the density of PBSs in the heart and kidney remained reduced. The affinity of PBSs for the ligand [³H]PK 11195 in the cerebral cortex and heart was not affected by the drug treatment or withdrawal. The CPZ‐induced alterations in PBSs may be relevant to the effects of the drug on CNS and/or peripheral organs.