Effect of chronic haloperidol treatment on peripheral benzodiazepine binding sites in cerebral cortex of rats

The effects of 21 days of haloperidol treatment on central benzodiazepine (BZ) receptors in the cerebral cortex of rats and on peripheral-type BZ binding sites (PBS) in the cerebral cortex and heart of rats were studied. Neuroleptic treatment did not affect the maximal binding capacity or the affinity of the central BZ receptor to 3H-flunitrazepam. Chronic haloperidol treatment resulted in a significant increase of 38% in PBS density in the cerebral cortex, with no alteration in PBS density in the heart. No alteration in PBS affinity for its ligand 3H-PK 11195 was observed, either in the cerebral cortex or in the heart. The modulatory effect of chronic haloperidol administration on PBS density in the brain may be related to some of the neurobehavioral or hormonal effects of the drug.