AJP - Endocrinology and Metabolism, Vol 243, Issue 3 188-E195, Copyright © 1982 by American Physiological Society
Site of estrogen action in rabbit ovarian tissue
J. A. Holt, R. J. Dinerstein and M. A. Lorincz
In superovulated or naturally mated pseudopregnant rabbits, an abrupt
premature decline of progesterone production by the corpus luteum occurs
after removal of polydimethylsiloxane capsules filled with 17
beta-estradiol. Reinsertion of the estradiol-filled capsules stimulates a
striking restoration of progesterone production. We have given
[3H]estradiol by arterial infusion to anesthetized rabbits to determine by
cellular autoradiography whether the exogenous estradiol localizes to
luteal tissues responsible for progesterone production. Autoradiography
with both freeze-dried and touch-thaw mounted preparations demonstrated
that tritium activity localized to the nuclei of luteal cells and that such
uptake could be blocked by radioinert diethylstilbestrol. We extracted the
tritium activity sequestered in vivo by the corpora lutea and
cocrystallized the extract with 14C-labeled and radiostable 17
beta-estradiol to confirm its presence (greater than 90%) as [3H]estradiol.
In addition, we were able to demonstrate that radiostable
diethylstilbestrol blocked ovarian uptake of 16 alpha-125I-17
beta-estradiol in vivo. In concert, these observations provide compelling
evidence that the exogenous estradiol responsible for restoring
progesterone production may act through an estrogen-specific mechanism
directly in the luteal cells.
