Inhibition of uterine prostaglandin-F 2α production by bovine conceptus secretory proteins

Abstract

The effect of bovine conceptus secretory proteins (CSP) on uterine prostaglandin (PG)-F 2α 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 E 2 (3 mg) to stimulate uterine PGF 2α production. Plasma concentrations of progesterone (P 4) and 15-keto-13,14-dihydro-PGF 2α (PGFM) were determined by RIA. The PGFM responses following E 2 challenge were decreased (p<0.01) for cows receiving CSP versus serum proteins into the uterine lumen. Individual PGFM, P 4 and cycle length responses are discussed. Data suggest that proteins secreted by the bovine conceptus suppress uterine PGF 2α production during pregnancy recognition in the cow.