Prostaglandin E2, prostaglandin f2α and endothelin-1 production by cow oviductal epithelial cell monolayers: Effect of progesterone, estradiol 17β, oxytocin and luteinizing hormone

Abstract

The optimal oviductal environment, including contractile activity for gamete transport, fertilization and early embryonic development, is mediated by physiological and anatomical changes in the oviduct during the estrous cycle. Oviductal epithelial cell culture was utilized to investigate the effect of ovarian steroids (progesterone [P4]and estradiol 17β[E2]), oxytocin (OT) and luteinizing hormone (LH) on the local production of prostaglandin E2 (PGE2), prostaglandin F2α (PGF2α) and endothelin-1 (ET-1) in the cow oviduct. Epithelial cells isolated from oviducts collected during the follicular phase were cultured in M199 under standard culture conditions until monolayer formation. Then the cells were trypsinized and plated at a density of 3 x 10 4 /mL/well and cultured again until subconfluency, at which time the cells were incubated for 4 or 24 h with M199 only (control), high P4 (H-P4;1μg/mL), low P4 (L-P4;10 ng/mL), E2 (1 ng/mL), LH (10 ng/mL),OT (10 −9 M) ET-1 (10 −9 M), PGE2 (10 −8 M) PGF2a (10 −9 M) or their combination (H-P4+E2, L-P4+E2, LH+E2, ET-1+E2, L-P4+E2+LH and H-P4+E2+LH). The production of both PG and ET-1 was increased by E2+low P4 and LH+E2+low P4 (P<0.05), while LH+E2 enhanced the production of PGF2a and ET-1 (P<0.05). Moreover, E2+ET-1 stimulated PG production (P<0.05). However, OT had no effect on the production of any of these substances. These results suggest that the preovulatory LH surge, together with locally re-circulated high levels of E2 from the Graafian follicle and basal P4 from regressing corpus luteum (CL), induces the maximum stimulatory effect on oviductal PGE2, PGF2a and ET-1 production during the periovulatory period. Consequently, the elevated local ET-1 concentration during periovulatory period may induce the high contractile activity of the oviduct and, at the same time, the stimulation of PG production. Thus, ET-1 may act as a local amplifier for oviductal PG production stimulated by LH and ovarian steroids.