Suppressive Effect of Prostaglandin D2 on Prolactin Secretion from Rat Anterior Pituitary

Prostaglandin D2 (PGD2) was investigated for its effect on prolactin (PRL) secretion from rat anterior pituitary in vitro and in vivo. Significant suppression in the release of PRL was observed when the anterior pituitaries were incubated for 4 hours in vitro in the presence of more than 100 μg of PGD2/ml incubation medium. In the second experiment, animals received intravenous injections of PGD2 after pretreatment of ovariectomized mature rats with estrogen and progesterone. Thirty minutes after injection of 250 μg or 500 μg of PGD2, serum PRL levels were significantly lower than levels before the PGD2 injection. The injection of the vehicle control did not affect serum PRL levels. These results suggest that at high dosages PGD2 suppresses PRL secretion by acting directly on the rat anterior pituitary gland.