Induction of prostaglandin endoperoxide synthase 2 in the follicles of equine chorionic gonadotropinhuman chorionic gonadotropin treated prepubertal gilts

Prostaglandin G/H synthase-2 (PGHS-2) is a key rate limiting enzyme in the prostaglandin (PG) biosynthetic pathway, and PG synthesis is required for ovulation in pigs. The objective of this study was to characterize the expression and regulation of PGHS-2 in porcine follicles prior to ovulation. The combination of equine chorionic gonadotropin (eCG; 750 IU) followed by human chorionic gonadotropin (hCG; 500 IU) 72 h later was used to induce ovulation in prepubertal gilts. Previous studies have shown that ovulation is generally induced between 40 and 44 h post-hCG in this model. Ovariectomies were performed at 0, 24, 30, 34 and 38 h post-hCG (n = 4 or 5 animals per time-point), and all follicles larger than 4 mm in diameter were isolated. The regulation of PGHS-1 and PGHS-2 proteins was studied by immunohistochemistry and Western blot analyses, whereas the regulation of PGHS-2 mRNA was studied by Northern blot. PG production was assessed by radioimmunoassay (RIA). (Abstract shortened by UMI.