Effect of clozapine on dopamine-induced inhibition of prolactin release from cultured rat pituitary cells.

Although the atypical antipsychotic agent clozapine has little propensity to induce hyperprolactinemia in humans it increases serum prolactin levels in the rat. In this study, the effects of clozapine and of some typical antipsychotic drugs on basal and dopamine-mediated prolactin secretion from cultured rat pituitary cells were compared. Despite being less potent than the other antipsychotic agents tested, clozapine reverted the effect of dopamine on prolactin secretion in vitro. This finding suggests that clozapine interferes with dopamine receptors in the pituitary gland.