Regional blockade by neuroleptic drugs of in vivo 3H-spiperone binding in the rat brain. Relation to blockade of apomorphine induced hyperactivity and stereotypies.

The regional prevention by neuroleptic drugs of specific in vivo 3H-spiperone binding was studied in the rat brain. L-sulpiride, thioridazine and clozapine was found to reduce the 3H-spiperone binding selectively in the olfactory tubercle, septum, substantia nigra region and frontal cortex but not the striatum at dose levels which preferentially block apomorphine (APO) induced hyperactivity. The maximal prevention of specific 3H-spiperone binding by l-sulpiride and clozapine reached 60-80% in the former structures while the displacement of striatal 3H-spiperone binding did not exceed 40%. In contrast to l-sulpiride, thioridazine and clozapine both chlorpromazine and haloperidol reduced the 3H-spiperone binding to the same extent in all regions studied. Chlorpromazine and haloperidol were potent in prevention of striatal 3H-spiperone binding in vivo which reached 60-80% in this structure.