EFFECTS OF PROSTAGLANDIN-F-2-ALPHA AND INDOMETHACIN ON UTERINE CONTRACTION IN HENS

Roles of prostaglandins (PGs) in the regulation of uterine contraction (UC) in hens during the ovulatory cycle were studied. Prostaglandin F(2α) (PGF(2α)) (0.25 or 1.0 μg/hen) injected either pre- or postoviposition elicited an increase in uterine electrical activity in a dose related manner. Injection 2 h prior to oviposition induced premature oviposition. Indomethacin (5 mg/hen) given 4 h before the expected time of oviposition invariably depressed the occurrence of the oviposition peak of UC and delayed oviposition. In contrast, indomethacin administered 4 h before the expected time of the ovulation of the first egg (C1) of the clutch did not inhibit either the occurrence of the preovulatory peak of UC or ovulation. These results indicate that PGs probably play the primary role in causing the marked UC at the time of normal oviposition.