PGE(1) OR PGE(2) NOT LH REGULATES SECRETION OF PROGESTERONE IN-VITRO BY THE 88-90 DAY OVINE CORPUS-LUTEUM OF PREGNANCY

Secretion of progesterone in vitro by mature day 8 ovine corpora lutea (CL) of the estrous cycle was increased linearly by ovine LH (1, 10 a nd 100 ng/ml) or prostaglandin E-2 (PGE(2)) 1, 10 and 100 ng/ml) in a dose dependent manner (P less than or equal to 0.05). Progesterone sec retion in vitro by 88-90 day ovine CL of pregnancy was not affected P greater than or equal to 0.05 by LH (1, 10 and 200 ng/ml) while prosta glandin E-1 (PGE(1)) 1, 10 and 100 ng/ml) increased (P less than or eq ual to 0.05) secretion of progesterone in a dose dependent manner and PGE(2) (1, 10 and 100 ng/ml) increased (P less than or equal to 0.05) secretion of progesterone only at the 100 ng/ml dose. Day 8 ovine CL o f the estrous cycle did not secrete (P greater than or equal to 0.05) detectable quantities of prostaglandin F-2 alpha (PGE(2) alpha) or pro staglandin E (PGE) while 88-90 day ovine CL of pregnancy secrete PGE ( P less than or equal to 0.05) but not PGF(2) alpha (P greater than or equal to 0.05). Regulation of PGE secretion by 88-90 day ovine CL of p regnancy may be via pregnancy specific protein B (PSPBJ, which increas ed (P less than or equal to 0.051 PGE and progesterone but not PGF(2) alpha (P greater than or equal to 0.05) secretion. Secretion of proges terone by CL of 88-90 days of pregnancy was not affected by IGF(1), IG F(2), PAF-16, PAF-18, oxytocin, PGI(2), PGD(2) or leukotriene C-4 (P g reater than or equal to 0.05). It is concluded that PGE(1) or PGE(2) b ut not LH regulates secretion of progesterone in vitro by 88-90 day ov ine CL of pregnancy. In addition, it is concluded that 88-90 day ovine CL of pregnancy secretes it's own luteotropin, which is PGE. Secretio n of PGE by ovine CL of pregnancy may be regulated by PSPB.