|Abstract or Summary
- The ability of ovine endometrium incubated in vitro with
estradiol -17(3 to synthesize a specific induced protein (IP) was
studied. Endometrium from cycling, pregnant and ovariectomized
ewes was used.
Twelve ewes were allotted in equal numbers to be sacrificed on
days 0 (estrus), 3, 6, or 10 of the estrous cycle. In addition uteri
from nonpregnant ewes (day 14 or 15, N = 3) were compared with day
15 pregnant ewes (N = 3).
Experiment 2 involved 16 ovariectomized ewes assigned randomly
to one of four treatment regimes. The ewes were treated as
follows: a) controls, no exogenous steroids, b) estradiol -17β,
c) progesterone and d) progesterone plus estradiol. Estradiol was
packed into silastic capsules and implanted subcutaneously on day 1 of
treatment. Progesterone (15 mg 2x daily) or vehicle (oil) were injected for 5 consecutive days beginning 48 hr (day 3) after implantation
of estradiol. All ewes were sacrificed on the morning of day 8.
Blood samples were taken at sacrifice and estradiol and progesterone
levels were measured. The ewes treated with estradiol tended to
have increased estradiol levels and ewes receiving progesterone had
significantly higher serum progesterone levels.
Upon sacrifice of the ewes, the uterus was removed and transported
to the laboratory. Three-50 mg endometrial segments were
incubated for 1 hr with either 2.5 x 10⁻⁸ M estradio1-17β (treated) or
ethanol (control), followed by a 2 or 4 hr incubation with labelled
amino acids. Treated and control tissues were homogenized together
and the resulting supernatant was stored at -20 C until electro
phoresed. Following disc gel electrophoresis, the gels were placed
into a dye for staining or were fixed in acetic acid. The gels fixed
with acetic acid were sliced into sections and then counted in a
Experiments utilizing immature rat uteri were conducted to
verify that IP synthesis in the rat uterus could be detected in our
laboratory. Induced protein was detected following estradiol stimulation
in vivo and in vitro.
Synthesis of an estradiol-induced endometrial protein was not
detected during the ovine estrous cycle, on day 15 of pregnancy or in
steroid-treated ovariectomized ewes. However, increased incorporation of both isotopes, running in front of the tracker dye,
was detected in two of the four ewes in both the control and estradioltreated
ovariectomized ewes. This increased isotope incorporation
was detected in all four ewes receiving progesterone injections and
was not present in any of the ewes receiving both estradiol and
progesterone. Problems with excess estradiol during the in vitro
incubation probably prevented any expression of IP during the estrous
cycle experiment (experiment 1).
No substantial change in the prealbumin, non-specific protein
patterns were observed. Protein profiles of uteri varied from 1 to 3
bands during the estrous cycle and day 15 of pregnancy. The number
of uterine prealbumin bands observed in the ovariectomized ewes
receiving exogenous steroids varied from 0 to 4 within and among the