Dopamine inhibits 32P incorporation into phosphatidylinositol in the anterior pituitary gland of the rat.

The in vitro effect of dopamine, haloperidol and pimozide on 32Pi incorporation into phosphatidylinositol, phosphatidylcholine and phosphatidylethanolamine by anterior pituitary glands was studied. Dopamine decreased the incorporation of 32Pi into phosphatidylinositol in a dose-related manner without affecting phosphatidylcholine and phosphatidylethanolamine. Haloperidol and pimozide did not modify 32Pi incorporation into these phospholipids by themselves but completely reversed the inhibitory effect of dopamine on phosphatidylinositol. The inhibition of 32Pi incorporation into phosphatidylinositol synthesis in the presence of 500 nM dopamine was significant at 20 min of incubation and maximal at 30 min. The possibility that a decrease in phosphatidylinositol cleavage and turnover may be involved in the inhibitory regulation of prolactin secretion by DA is suggested.