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Biology of Reproduction, Vol 22, 1142-1148, Copyright © 1980 by Society for the Study of Reproduction
1 Reproductive Endocrinology Program,
Department of Pathology and Department of Physiology,
The University of Michigan,
Ann Arbor, Michigan 48109
and
Department of Physiology and Biophysics,
University of Illinois at the Medical Center,
Chicago, Illinois 60680 The luteotropic effect of testosterone was investigated in pregnant rats by determining some of
the early changes in luteal function associated with the action of this hormone after injection of
LH antiserum. The injection of LH antiserum on Day 11 of pregnancy caused a decrease in serum
progesterone and in luteal estradiol concentration within 6 h, and subsequently led to abortion.
Treatment with a low dose of testosterone via Silastic capsule prevented abortion and the decrease
in luteal estradiol and rapidly restored serum progesterone to values which were maintained at
elevated, though distinctly lower, values than in control pregnant rats. The reduced serum progesterone in testosterone-treated rats was interpreted as the result of increased formation of 20
-dihydroprogesterone, which appeared in high concentrations within 24 h after injection of LH
antiserum and remained elevated through Day 15 of pregnancy, the end of the experiment. In LH
antiserum-treated rats without testosterone, the increment in 20
-dihydroprogesterone was also
apparent within 24 h, but did not compensate for the sustained loss of progesterone secretion
which preceded abortion. Corpora lutea retained aromatase activity in rats aborting after administration of LH antiserum, suggesting that this enzyme was not rate-limiting for estradiol formation
in these regressing corpora lutea. These, together with other studies, provide further impetus to the
idea that estrogens formed in luteal tissue mediate the sustained progesterone steroidogenic effect
of LH. However, one important action of LH may be the suppression of 20
-dihydroprogesterone
secretion, thus augmenting the secretion of progesterone.
Accepted on March 31, 1980
This article has been cited by other articles:
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