Local distributions of oviductal estradiol, progesterone, prostaglandins, oxytocin and endothelin-1 in the cyclic cow

Abstract

The cyclic patterns of hormones which regulate the activity of the oviduct in the cow have not been adequately reported. We studied progesterone (P 4), estradiol 17β (E 2), prostaglandin E 2 (PGE 2), prostaglandin F 2α (PGF 2α), oxytocin (OT) and endothelin-1 (ET-1) concentrations in the cow oviduct. Reproductive tracts from cyclic Holstein cows in the follicular phase (n=5), post ovulation phase (n=5) and luteal phase (n=5) were collected at a slaughterhouse. Oviducts were separated from the uterus, the lumen vas washed with physiological saline, and the enveloping connective tissues were removed. The fimbria was then separated at first and then the rest was divided into 2 1 arts of equal length (proximal and distal). After extraction, levels of different hormones in the tissues were measured using double antibody enzyme immunoassays (EIAs). There were no differences in any hormone concentration between the 3 parts of the oviduct at any stage of the estrous cycle. The highest concentration of oviductal P 4 was observed during the luteal phase and in the oviduct ipsilateral to the functioning CL. Oviductal OT was unchanged throughout the cycle. The highest E 2 concentration was observed during the follicular phase in the oviduct ipsilateral to the dominant follicle. The oviduct ipsilateral to the dominant follicle during the follicular phase and ipsilateral to the ovulation site post ovulation showed higher levels of PGE 2PGF 2α and ET-1 than those on the contralateral side or during the luteal phase. The highest PGE 2 was observed in the oviduct ipsilateral to the ovulation site during the post ovulation phase. The results suggest that the ovarian products (P 4, OT and E 2) and the local oviductal products (PGE 2, PGF 2α, and ET-1) may synergistically control oviductal contraction for optimal embryo transport during the periovulatory period, and provide further evidence for the local delivery of ovarian steroids to the adjacent reproductive tract.