HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) All Versions of this Article: 68/5/1764    most recent biolreprod.102.008821v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Zapatero-Caballero, H. Articles by Fernandez-Vazquez, G. Search for Related Content PubMed PubMed Citation Articles by Zapatero-Caballero, H. Articles by Fernandez-Vazquez, G. Agricola Articles by Zapatero-Caballero, H. Articles by Fernandez-Vazquez, G.

Gonadotropin-Releasing Hormone Receptor Gene Expression During Pubertal Development of Male Rats¹

Servicio de Endocrinología, Hospital Carlos III, Instituto de Salud Carlos III, 28029 Madrid, Spain

Appropriate expression of the GnRH receptor (GnRH-R) in gonadotropes is critical for GnRH signaling and hence for gonadotropin secretion and sexual development. In the present work, we have studied the ontogeny of the steady-state GnRH-R mRNA levels in pituitaries of male rats from Day 5 to Day 55, when sexual maturity is attained. Developmental changes of gonadotropin subunit (, FSHß, and LHß) mRNA levels were also assessed. In addition, the role of the endogenous GnRH on the maturational changes of GnRH-R and gonadotropin subunit gene expression was investigated. Messenger RNA levels were determined by Northern blot analysis of total RNA from anterior pituitaries. Amounts of the most abundant (5.0 kb) GnRH-R mRNA increased slowly from Day 5 through the infantile and the juvenile periods, to peak at Day 35 (12-fold increase vs. Day 5). Thereafter, the levels of the GnRH-R mRNA decline slightly until Day 55 (33% decrease vs. Day 35). Parallel changes were observed on the 4.5-kb transcript of the GnRH-R gene. Alpha subunit mRNA was easily detected at Day 5, and its levels increased progressively through the infantile period (2.5-fold increase) and peaked at Day 25 (3.3-fold increase vs. Day 5) with a smooth nonstatistically significant increment until Day 35; then it decreased by 41.5% at Day 55. FSHß and LHß mRNA levels rose slowly until Day 25. A sharp rise occurred thereafter to reach maximum levels at Day 35 (5.8-fold for FSHß and 3.8-fold for LHß vs. Day 25). Thereafter, the levels of both mRNAs fell until Day 55 (44.1% decrease for FSHß and 37.1% decrease for LHß vs. Day 35). To ascertain whether developmental activation of the GnRH-R and gonadotropin subunit gene expression is GnRH dependent, we have studied the effect of blocking the endogenous GnRH action by treating developing male rats with the specific GnRH antagonist cetrorelix (1.5 mg/kg body weight/week, s.c.) through the infantile (Days 5–20) and the juvenile periods (Days 20–35). Cetrorelix completely blocked the rise of levels of the two most abundant species, 5.0 kb and 4.5 kb, of the GnRH-R mRNA, during both the infantile and the juvenile periods. Cetrorelix also abolished the developmental rise of the gonadotropin ß subunit mRNAs during the two periods of the study. In contrast, the subunit gene expression was not altered by cetrorelix treatment during any of the two periods. These data demonstrate that sexual maturation of male rats is accompanied by a progressive and concerted induction of GnRH-R and gonadotropin subunit gene expression. Developmental activation of GnRH-R and gonadotropin ß subunit genes is GnRH dependent. The apparent GnRH-independent regulation of the -glycoprotein subunit mRNA levels may be due to the contribution of thyrotropes and perhaps to the presence of exclusive regulatory signals for this gene.

¹ Parts of this work were presented at the 81st Annual Meeting of the Endocrine Society, San Diego, CA, 12–15 June 1999, and at the 82nd Annual Meeting of the Endocrine Society, Toronto, ON, Canada, 21–24 June 2000. This work was supported by grants PM95-212 from the Ministerio de Educación y Ciencia and 99/0412 from the Fondo de Investigación Sanitaria (to G.F.V.) and by a predoctoral fellowship from the Instituto de Salud Carlos III (to H.Z.C.).

² Correspondence: Gumersindo Fernandez Vazquez, Servicio de Endocrinología, Hospital Carlos III, Instituto de salud Carlos III, Sinesio Delgado 10, Madrid 28029, Spain. FAX: 34 91 733 6614; gfernandez.hciii{at}salud.madrid.org

This article has been cited by other articles:

				J. P. Moore ,Jr. and S. J. Winters Weaning and the Developmental Changes in Follicle-Stimulating Hormone, Pituitary Adenylate Cyclase-Activating Polypeptide, and Inhibin B in the Male Rat Biol Reprod, April 1, 2008; 78(4): 752 - 760. [Abstract] [Full Text] [PDF]

				S. J Winters and J. P Moore Intra-pituitary regulation of gonadotrophs in male rodents and primates Reproduction, July 1, 2004; 128(1): 13 - 23. [Abstract] [Full Text] [PDF]

				H. Zapatero-Caballero, F. Sanchez-Franco, C. Fernandez-Mendez, M. Garcia-San Frutos, L. M. Botella-Cubells, and G. Fernandez-Vazquez Gonadotropin-Releasing Hormone Receptor Gene Expression During Pubertal Development of Female Rats Biol Reprod, February 1, 2004; 70(2): 348 - 355. [Abstract] [Full Text] [PDF]