Prostaglandin E 2 and progesterone during the estrous cycle of the pig

Abstract

The possible role of endogenous PGE 2 in corpus luteum function during the estrous cycle of the pig was examined. A catheter was placed in an ovarian vein of each of three sows and in the posterior vena cava of six gilts. Blood samples were collected twice daily. Blood was also collected every 10 min for 6 h from the sows and for 12 h from the gilts during early, mid and late estrous cycle. In the sows, average serum PGE 2 levels tended to be higher on days 2 and 9 than on day 16 postestrus ( P < 0.1). Average PGE 2 levels in the gilts were higher during the late phase than during the early and mid phases of the cycle ( P < 0.05). Average progesterone levels in both the sows and the gilts were several fold higher during the mid phase than during the early and late phases of the cycle. Results from this study do not support the hypothesis that endogenous PGE 2 is antiluteolytic because the average PGE 2 levels in the gilts and sows were either higher or not lower during the regression phase of the corpus luteum than during earlier stages of the cycle.