Effect of ovulation and hormonal treatment on the in vitro response of rabbit oviducts to prostaglandins E1 and F2alpha

Abstract

Rabbit oviductal circular muscle isometric contractile response was measured in relation to treatment with prostaglandin E1 (PGE1) and prostaglandin F2alpha (PGF2alpha). PGE1 (1 mug/ml) inhibition of the contractile response of the rabbit oviduct to field stimulation was increased in the proximal isthmus after ovulation. Estrogen and progesteron, in doses known to alter ovum transport, did not affect the response of the oviduct to PGE1. In comparison to the response of estrous tissues, the stimulatory effect of PGF2alpha on the isthmus was decreased 24 hours after administration of human chorionic gonadotropin (HCG). Treatment with estrogen and progesterone did not affect these postovulatory changes. The response of the ampullary-isthmic junction to PGF2alpha was significantly reduced 72 hours after administration of HCG. Neither ovulation nor steroid treatment affected the response of the ampulla to PGF2alpha. Changes in the sensitivity of the oviduct to prostaglandins after ovulation may be necessary for successful ovum transport.