CHRONIC HALOPERIDOL TREATMENT ENHANCES BINDING TO NMDA RECEPTORS IN RAT CORTEX

HYPERACTIVITY of the dopaminergic system and a hypoglutamatergic state have been hypothesized to underlie schizophrenia. It has also been pr oposed that neuroleptics may interact not only with the dopaminergic s ystem but also with the glutamatergic system. We found that daily intr aperitoneal injections of haloperidol (1 mg kg-1) for 21 days resulted in increased binding (10-20%) to the NMDA type of glutamate receptors in the outer layers of rat parietal cortex. Quantitative receptor aut oradiography indicates that the action of haloperidol is regionally sp ecific since no changes in NMDA receptors were found in the hippocampu s and thalamus. Our data suggest that haloperidol may exert its antips ychotic effects by enhancement of glutamatergic functions as well as b y the blockade of dopamine receptors.