PROSTAGLANDINS AND SEX STEROIDS FROM CORPORA-LUTEA OF PREGNANT MARES - IN-VITRO STUDIES

To delineate endocrine mechanisms regulating equine luteal function an d the possible functional differences between one month and three mont h corpora lutea of pregnancy (CL), the in vitro basal releases of pros taglandin F (PGF), prostaglandin E(2) (PGE(2)), progesterone, and 17 b eta-estradiol by one and three month CL of pregnant mares were evaluat ed. in addition, the in vitro effects of PGF(2 alpha), PGE(2), progest erone and 17 beta-estradiol on synthesis of prostaglandins (PGs) and s ex steroids were studied. PGF, PGE(2), and 17 beta-estradiol secretion was higher in one month than in three month CL, while progesterone wa s secreted similarly by both types of CL. PGE(2) treatment decreased 1 7 beta-estradiol in one month CL; progesterone increased PGE(2) in one and three month CL; Z7 beta-estradiol increased PGE(2) in one month C L. This study suggests that, in one month CL, PGE(2) production could be regulated by progesterone and 17 beta-estradiol, while, in three mo nth CL, this prostaglandin seems to be under the control of progestero ne alone.