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

摘要

Reproductive tracts were collected from 15 cyclic Holstein cows in the follicular phase, post ovulation phase and luteal phase. Oviducts were separated from the uterus, the lumen was washed with physiological saline, and the enveloping connective tissues were removed. The fimbria was then separated and the rest of the oviduct was divided into 2 parts of equal length (proximal and distal). Hormones were extracted from the tissues, and their concentrations were measured using double antibody enzyme immunoassays. There was no difference in the concentration of progesterone, oestradiol 17beta, prostaglandin E2 (PGE2), prostaglandin F2alpha (PGF2alpha), oxytocin or endothelin-1 between the 3 parts of the oviduct at any stage of the oestrous cycle. Progesterone concentration was highest during the luteal phase; the oviduct ipsilateral to the functioning corpus luteum had a 5-fold higher concentration than the contralateral oviduct. Oxytocin level was unchanged throughout the cycle. The highest oestradiol concentration was observed during the follicular phase in the oviduct ipsilateral to the dominant follicle. During the follicular phase and after ovulation, the oviduct ipsilateral to the dominant follicle and the ovulation site after ovulation showedhigher levels of PGE2, PGF2alpha and endothelin-1 than the contralateral oviduct; all values were lower during the luteal phase. The highest PGE2 concentration was observed in the oviduct ipsilateral to the ovulation site during the post ovulation phase. The results suggest that ovarian products (progesterone, oxytocin and oestradiol) and the local oviductal products (PGE2, PGF2alpha and endothelin-1) may synergistically control oviductal contraction for optimal embryo transport during the periovulatory period. They also provide evidence for the local delivery of ovarian steroids to the adjacent reproductive tract.