Prostaglandins and sex steroids from corpora lutea of pregnant mares. In vitro studies.

To delineate endocrine mechanisms regulating equine luteal function and the possible functional differences between one month and three month corpora lutea of pregnancy (CL), the in vitro basal releases of prostaglandin F (PGF), prostaglandin E2 (PGE2), progesterone, and 17 beta-estradiol by one and three month CL of pregnant mares were evaluated. In addition, the in vitro effects of PGF2 alpha PGE2, progesterone and 17 beta-estradiol on synthesis of prostaglandins (PGs) and sex steroids were studied. PGF, PGE2, and 17 beta-estradiol secretion was higher in one month than in three month CL, while progesterone was secreted similarly by both types of CL. PGE2 treatment decreased 17 beta-estradiol in one month CL; progesterone increased PGE2 in one and three month CL; 17 beta-estradiol increased PGE2 in one month CL. This study suggests that, in one month CL, PGE2 production could be regulated by progesterone and 17 beta-estradiol, while, in three month CL, this prostaglandin seems to be under the control of progesterone alone