help button home button Endocrine Society Endocrinology
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
This Article
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow Request Copyright Permission
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Webb, R.
Right arrow Articles by Fitzpatrick, K. E.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Webb, R.
Right arrow Articles by Fitzpatrick, K. E.

Endocrinology, Vol 108, 1178-1185, Copyright © 1981 by Endocrine Society

ARTICLES

Control of the preovulatory gonadotropin surge in the ewe

R Webb, BG England and KE Fitzpatrick

The aims of this study were to determine the effect of ovariectomy on the release of LH and FSH during the preovulatory gonadotropin surge and to ascertain, by the use of sodium pentobarbitone (NaPb), if the secretion of these pituitary hormones requires continuous stimulation from the hypothalamus. Sheep were treated with NaPb for 2 h beginning 1) immediately before the gonadotropin surge, 2) during the ascending limb of the gonadotropin surge, and 3) during the descending limb of the gonadotropin surge. Ewes were ovariectomized (ovx) at each of the time periods listed above, and intact ewes included were at times 2 and 3. A group of intact ewes was given 100 microgram gonadotropin- releasing hormone (GnRH) in addition to NaPb at time 2, NaPb given during the ascending limb of the gonadotropin surge caused a transient fall in peripheral LH and FSH; however, the release of gonadotropins was reinitiated and the surge continued when the ewes recovered from anesthesia. Treatment with NaPb after the apex of the gonadotropin surge did not affect circulating levels of LH and FSH. Ewes given NaPb and ovx before the initiation of the gonadotropin surge released significantly less LH and FSH during the surge than the other treatment groups. The total amounts of LH and FSH released in intact and ovx ewes treated with NaPb after the surge was initiated were not different than those levels in the saline-treated controls. Intact ewes treated with 100 micrograms GnRH also released an amount of LH similar to that in the control group. We conclude that gonadotropin release from the pituitary gland requires the continual presence of GnRH during the ascending limb of the preovulatory gonadotropin surge, and that once the surge has been triggered, the ovaries do not appear to be required for further hypothalamic stimulation.


This article has been cited by other articles:


Home page
 EndocrinologyHome page
H. I'Anson, J. M. Manning, C. G. Herbosa, J. Pelt, C. R. Friedman, R. I. Wood, D. C. Bucholtz, and D. L. Foster
Central Inhibition of Gonadotropin-Releasing Hormone Secretion in the Growth-Restricted Hypogonadotropic Female Sheep
Endocrinology, February 1, 2000; 141(2): 520 - 527.
[Abstract] [Full Text] [PDF]


HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
Endocrinology Endocrine Reviews J. Clin. End. & Metab.
Molecular Endocrinology Recent Prog. Horm. Res. All Endocrine Journals
Copyright © 1981 by The Endocrine Society