Interleukin 1β-induced synthesis and secretion of prostaglandin E₂ in the porcine uterus during various periods of pregnancy and the estrous cycle.

Peri-implantation porcine embryos express interleukin-1β (IL-1β), which could affect uterine activity during early pregnancy. In vitro studies were conducted to determine if IL-1β stimulates secretion of PGE₂ and expression of cyclooxygenase-2 (COX-2) mRNA and microsomal PGE synthase-1 (mPGES-1) mRNA in uterine tissues harvested from pigs on days 10 to 11, 12 to 13 and 15 to 16 of pregnancy and the estrous cycle. IL-1β (10 ng/ml) increased PGE₂ secretion and mPGES-1 mRNA expression in uterine tissues isolated from pigs between days 10 to 13 of pregnancy and the estrous cycle. IL-1β stimulated PGE₂ and mPGES-1 mRNA expression only in cyclic uterine tissues on days 15 to 16. Interleukin-1β increased COX-2 mRNA expression in the endometrial tissues of pregnant and cyclic pigs harvested on days 10 to 13. It stimulated COX-2 expression in pregnant pigs' myometrial tissues on days 10 to 11, and on days 15 to 16 in tissues from both pregnant and cyclic pigs. The uterine secretion of PGE₂ in response to IL-1β was determined by local intrauterine concentrations of P₄ and E₂. This study demonstrates that IL-1β activates expression of mPGES-1 mRNA in uterine tissues to stimulate synthesis and secretion of PGE₂ on days 10 to 13 of both pregnancy and the estrous cycle. The profile of COX-2 mRNA expression in the myometrium differs from its profile in the endometrium. This work provides new insight on the role of IL-1β in PGE₂ production to overcome luteolysis in pregnant pigs.