Rj. Moffatt et al., ENDOCRINE AND ENDOMETRIAL SECRETORY PROTEIN-CHANGES ASSOCIATED WITH UTERINE RECEPTIVITY IN SHEEP, Domestic animal endocrinology, 10(2), 1993, pp. 117-126
Crossbred ovariectomized ewes were treated with steroid therapies dete
rmined previously to be adequate (progesterone-primed) or inadequate (
unprimed) for embryonic development in order to determine actual serum
concentrations of replaced steroid hormones achieved by such treatmen
ts and to identify secreted endometrial proteins that might mediate ut
erine receptivity. Ewes received estradiol-17-beta on day 0, and on da
ys 1-4, either vehicle (unprimed; N=16) or progesterone (primed; N=16)
daily. All ewes then received ''estrus estradiol'' (at 8 hr-intervals
), followed by ''maintenance progesterone'' (at 12 hr-intervals), to m
imic endocrine profiles of intact ewes at and following estrus. Jugula
r blood samples were obtained at 4-hr intervals from 6 ewes/treatment
on day 0-15 to determine serum progesterone, estradiol, and PGFM conce
ntrations. Endometrium from two ewes/treatment on days 11-15 was cultu
red in vitro with [H-3]leucine and radiolabeled proteins in media were
analyzed electrophoretically. Results demonstrated that 1) treatments
generated transient serum estradiol levels slightly greater than thos
e reported in intact animals at estrus, 2) serum progesterone concentr
ations due to treatments were similar to those reported in the luteal
phase of intact ewes, 3) progesterone-priming was specifically associa
ted with a small, sustained (24-36 hr) elevation in serum PGFM, and th
at 4) priming was not associated with the presence or absence of major
, secreted endometrial proteins that might act either as factors requi
red for development or as embryotoxins. These results suggest that pos
itive effects of progesterone-priming on embryo survival are not due t
o pharmacological doses of exogenously administered hormones, nor are
due to changes in secretion of hormonally-regulated, major endometrial
proteins.