Effect of sultopride on prolactin secretion in rats

Oral administration of sultopride caused a significant and dose-related increase in serum prolactin levels in the rat. Sultopride was 4-6 times as potent as sulpiride in stimulating prolactin secretion. Both drugs produced much greater stimulations of prolactin release in female rats than in male rats, suggesting the sex difference in response to drugs. CB-154, a dopamine agonist, inhibited the sultopride-induced prolactin release. Stereoselective activity of sultopride-isomers was observed in increasing rat prolactin secretion. Sultopride had no significant effects on LH and FSH basal levels in female rats. In a successive study, basal prolactin levels in the male rat were higher at 2-3 days, but lower at 6 and 14 days. Prolactin response 1 hr after sultopride administration was observed throughout the experiments. Sultopride neutralized the dopamine-mediated inhibition of prolactin secretion from the anterior pituitary in vitro. These results suggest that sultopride, like sulpiride, stimulates prolactin secretion by blocking the dopamine receptor in the pituitary.