Acute and Chronic Effects of Haloperidol on Dopamine Fluorescence in the Median Eminence and on Plasma Prolactin Prolactin Levels in Rát

Abstract

Time course studies of the effects of haloperidol (2 mg/kg) on alphamethyltyrosine-induced dopamine fluorescence in the median eminence and on plasma prolactin levels showed that both dopamine turnover in the median eminence and prolactin levels are significantly increased 20 h after a single i.p. injection of haloperidol. Further, hypophysectomy prevents haloper idol-induced increase in dopamine turnover in the median eminence. Moreover, a marked increase in dopamine turnover in the median eminence was found 1, 5 and 10 weeks after chronic administration of haloperidol (about lmg/kg/day). Haloperidol administration for a week caused a significant elevation of plasma prolactin levels. Our histochemical data suggests that tolerance does not develop to the effect of haloperidol-induced prolactin on dopamine turnover in rat median eminence.