The effects of prostacyclin PGI 2 on prolactin secretion in vitro

Abstract

Continuously superfused rat anterior pituitary cells were used to study the effects of exogenous prostaglandins (PGs) and thromboxanes (TXz) on the secretion of prolactin (PRL). No change in hormone release was observed upon superfusion with TXB 2 (10 −5M) or the TX synthesis inhibitor, imidazole (1.5 mM). PGs A2, B2, d2, e1, e2, f1α, F2α, and endoperoxide analogs, U-44069 and U-46619, also had no effect on PRL secretion (all at 10 −5M), In contrast 10 −5M PGI2 was repeteadly found to stimulate PRL release to a level at least 125% above control, while producing no apparent change in the amount of hormone secreted in response to TRH. Somatostatin (SRIF), at a dose of 10 −M, maximally inhibited TRH-induces PRL output, but failed to alter the PRL response to PGI 2. These studies indicate that PGI 2 may have a direct effect on the anterior pituitary to modify PRL secretion.