Biol Reprod Keystone Symposia Conference on Frontiers in Reproductive Biology & Regulation of Fertility.
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
QUICK SEARCH:   [advanced]


     

BOR - Papers in Press, published online ahead of print May 26, 2004.
Biol Reprod 2004, 10.1095/biolreprod.104.029090
This Article
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow All Versions of this Article:
71/3/845    most recent
biolreprod.104.029090v1
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Right arrow Citation Map
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 reprints & permissions
Citing Articles
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Tsai, H.-W.
Right arrow Articles by Lu, J. K.H.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Tsai, H.-W.
Right arrow Articles by Lu, J. K.H.
Agricola
Right arrow Articles by Tsai, H.-W.
Right arrow Articles by Lu, J. K.H.
BIOLOGY OF REPRODUCTION 71, 845–852 (2004)
DOI: 10.1095/biolreprod.104.029090
© 2004 by the Society for the Study of Reproduction, Inc.

Neuroendocrinology

Temporal Changes Occur in the Neuroendocrine Control of Gonadotropin Secretion in Aging Female Rats: Role of Progesterone1

Houng-Wei Tsai3,5, Philip S. LaPolt4,5, Angelica P. Olcott5, and John K.H. Lu2,5,6,7

Departments of Obstetrics/Gynecology5 Neurobiology6 and the Laboratory of Neuroendocrinology of the Brain Research Institute,7 D. Geffen School of Medicine at University of California, Los Angeles, California 90095

The present study examined the gonadotropin surge-inducing actions of estradiol (E2), both alone and with progesterone (P4), in middle-aged, early persistent-estrous (PE) female rats that had become PE within 35 days. In addition, we also assessed the effect of P4 on the mating-induced gonadotropin surges in these acyclic animals. Early PE rats were ovariectomized and received E2 implants (Day 0). On Day 4, an s.c. injection of P4 (0.5 mg/ 100 g body weight) at 1200 h markedly increased plasma P4 and elicited both LH and FSH surges, whereas vehicle-treated controls displayed no rise in P4 or gonadotropins. This observation confirms that at middle age, female rats no longer respond to the positive-feedback stimulation of E2 on gonadotropin surges whenever the estrous cyclicity ceases. As PE continued, such a surge-inducing action of E2 plus P4 became diminished after 75 days of PE and disappeared thereafter. When caged with males, vehicle-treated early PE rats display a mating-induced increase in P4 from the adrenal along with small gonadotropin surges. The amplitude of these mating-induced gonadotropin surges was enhanced by supplementation with exogenous P4 in early PE rats. Our findings indicate that during the early phase of PE, the surge-inducing action of E2 and P4 remains intact but deteriorates as PE continues. Thus, a deficiency in P4 secretion during aging may contribute to the diminished gonadotropin surge response in the hypothalamic-pituitary axis and the subsequent cessation of estrous cyclicity.

1 Supported by NIA research grants AG01512 and AG04810 (J.K.H.L.) and AG10620 (P.S.L.), and by NICHD training grant T32-HD07228 (A.P.O.). A.P.O. is a postdoctoral trainee of the Laboratory of Neuroendocrinology, Brain Research Institute, UCLA.

2 Correspondence: John K.H. Lu, Division of Reproductive Endocrinology, Department of Obstetrics & Gynecology, CHS 22-172, D. Geffen School of Medicine at UCLA, 10833 Le Conte Avenue, Los Angeles, CA 90095-1740. FAX: 310 206 3670; jlu{at}mednet.ucla.edu

3 Current address: Department of Internal Medicine, Division of Endocrinology & Metabolism, University of Virginia, Charlottesville, VA 22908-0578

4 Current Address: Department of Biological Sciences, California State University Los Angeles, Los Angeles, CA 90032






HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
Copyright © 2004 by the Society for the Study of Reproduction.