|
|
||||||||
Biology of Reproduction, Vol 1, 189-196, Copyright © 1969 by Society for the Study of Reproduction
1 Department of Anatomy, Washington University School of Medicine, St. Louis, Missouri In order to study the effects of progesterone on pituitary gonadotrophin levels, the
steroid was administered (4 mg/day, subcutaneously) for a period corresponding to the
duration of pseudopregnancy (12-14 days) to intact, unilaterally and bilaterally spayed
rats (4-15 rats/group). In the bilaterally spayed rats the progesterone treatment was
started on the day of ovariectomy, 43 days after ovariectomy or 43 days after ovariectomy
+ estrogen priming. In all experiments, pituitary levels and in some experiments involving
bilaterally spayed rats, blood levels of FSH and LH were determined by HGG augmentation and OAAD methods, respectively. The administration of progesterone to intact and unilaterally spayed rats resulted in
increased pituitary LH stores which appeared comparable to those which have been
reported to normally occur at proestrus during the estrous cycle. In contrast, pituitary
FSH stores in these experiments were increased by more than three-fold (p < .05).
Progesterone treatment from the day of bilateral spaying failed to alter ovariectomy-induced increases in pituitary LH and FSH stores but was effective in decreasing postovariectomy rises in the plasma LH and FSH. In the long-term spayed rats, whether
primed with estrogen or not, progesterone failed to alter pituitary stores of LH and FSH.
It appears that progesterone, at least under the experimental conditions employed, in
addition to decreasing the release of LH, also decreases its synthesis in the pituitary. To
some extent, it is postulated, the same may be true with regard to FSH.
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |