EFFECTS OF INDOMETHACIN ON OVULATION AND LUTEAL FUNCTION IN GILTS

Experiments were carried out to determine the effects of inhibition of synthesis of prostaglandins by indomethacin on ovulation, oocyte maturation, luteinization and luteal function in prepubertal gilts treated with PMSG and hCG to induce follicular growth and ovulation. Indomethacin suppressed ovulation and the preovulatory rise in follicular fluid levels of prostaglandin E and prostaglandin F when administered at 20, 24 or 32 h after hCG injection. Oocyte maturation was not inhibited by indomethacin but progressive degeneration of the cumulus cell mass surrounding the oocyte occurred with time. Unruptured follicles in indomethacin treated animals progressively increased in size, blood and fibrin filled the central cavity and there was thickening and extreme vasodilatation of the thecal sheath; lutein cells lining the cavity appeared normal. Groups of PMSG/hCG treated gilts, treated with indomethacin 20 or 32 h after hCG treatment, had plasma progesterone profiles which were similar to those of untreated controls and indicated normal luteal function. These results support the hypothesis that ovarian synthesis of progstaglandin is a prerequisite in the sequence of events leading to follicle rupture and ovulation but do not implicate prostaglandins in oocyte maturation, or in development of normal luteal function.