Abstract: | The effect of bovine conceptus secretory proteins (CSP) on uterine prostaglandin (PG)-F2α production was evaluated in dairy cattle following injection of estradiol-17β. Intrauterine injections of dialyzed serum proteins (Control, n=5) or CSP (n=5) were administered from days 15 through 18 post-estrus. Following intrauterine treatments on day 18, all cows were injected with E2 (3 mg) to stimulate uterine PGF2α production. Plasma concentrations of progesterone (P4) and 15-keto-13,14-dihydro-PGF2α (PGFM) were determined by RIA. The PGFM responses following E2 challenge were decreased (p<0.01) for cows receiving CSP versus serum proteins into the uterine lumen. Individual PGFM, P4 and cycle length responses are discussed. Data suggest that proteins secreted by the bovine conceptus suppress uterine PGF2α production during pregnancy recognition in the cow. |