Effect of prostaglandin D2 on gonadotropin release from rat anterior pituitary in vitro

A new prostaglandin D2 (PGD2), which is highly concentrated in the rat hypothalamic-pituitary system, was investigated for its gonadotropin release and synthesis by radioimmunoassay (RIA). Significant increases in the release of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) were observed when the anterior pituitaries were incubated for 4 hours in vitro in the presence of 500 micrograms PGD2/ml incubation medium. Little change in LH and FSH contents in the rat anterior pituitary was observed between the control and PGD2-stimulated groups during incubation. In addition, more than 200 micrograms PGD2/ml induced a marked increase of cyclic adenosine 3',5' monophosphate (cAMP) formation in the rat anterior pituitary, and this was observed within 10 minutes after stimulation by PGD2. These data indicate that PGD2 directly induces a marked release of both LH and FSH from the gonadotrophs, and the mechanism of action of PGD2 could be mediated by cAMP formation.