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: 68/5/1577    most recent biolreprod.102.009944v1 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 Irusta, G. Articles by Tesone, M. Search for Related Content PubMed PubMed Citation Articles by Irusta, G. Articles by Tesone, M. Agricola Articles by Irusta, G. Articles by Tesone, M.

Steroidogenic Acute Regulatory Protein in Ovarian Follicles of Gonadotropin-Stimulated Rats Is Regulated by a Gonadotropin-Releasing Hormone Agonist¹

Instituto de Biología y Medicina Experimental (IBYME)-CONICET,³ Facultad de Ciencias Exactas, Universidad de Buenos Aires y Nacional de la Plata, 1428 Buenos Aires, Argentina Department of Cell Biology and Biochemistry,⁴ Texas Tech University Health Sciences Center, Lubbock, Texas 79430

The aim of the present study was to examine the acute and chronic effects of the gonadotropin-releasing hormone agonist (GnRH-a) leuprolide acetate (LA) on the expression of the steroidogenic acute regulatory protein (StAR), the cytochrome P450 side-chain cleavage enzyme (P450_scc), and steroid production in antral ovarian follicles obtained from prepubertal equine choriogonadotropin (eCG)-treated rats. Follicular contents of StAR and P450_scc proteins were measured by Western blotting following in vivo injection of eCG (control) and eCG+LA (LA) to prepubertal rats. Treatment with eCG for 2 h resulted in no change in StAR protein content, but it was markedly increased at 4 and 8 h after hormone treatment. However, coadministration of eCG+LA produced a significant increase (P < 0.05) in StAR protein levels at 2, 4, and 8 h when compared with eCG treatment. Acute and chronic treatment with either eCG or eCG+LA did not alter the P450_scc protein levels in freshly isolated follicles. The increase in StAR protein expression following LA treatment was qualitatively similar to StAR mRNA expression, as determined by quantitative reverse transcription-polymerase chain reaction (RT-PCR) analysis. Furthermore, administration of eCG demonstrated a time-dependent increase (2–8 h) in the levels of StAR mRNA, and these levels were markedly increased by eCG+LA. However, the temporal response pattern of StAR mRNA was much greater at 2 h following LA administration when compared with controls. In addition, 48 h of LA treatment in eCG-treated rats resulted in a significant increase (P < 0.05) in follicular progesterone levels, whereas significant decreases in androgen (testosterone and androsterone) and estradiol levels were observed. Similar results were obtained when serum androgens and estradiol were measured, but serum progesterone levels were unchanged. Collectively, these findings demonstrate that the inhibitory effect of LA on ovarian androgen and estradiol levels is related to changes in the follicular levels of StAR protein and steroid production.

¹ This study was supported by the ANPCYT (BID 1201 OC-AR PICT98/99:05-03512/05-06384), Roemmers Foundation, and PLACIRH (M.T.) and with funds from NIH grant HD 17481 and the Robert A. Welch Foundation (D.M.S.).

² Correspondence: Marta Tesone, Instituto de Biología y Medicina Experimental, Obligado 2490, 1428 Buenos Aires, Argentina. FAX: 54 011 4786 2564; mtesone{at}dna.uba.ar

This article has been cited by other articles:

				M. C. Peluffo, R. L. Stouffer, and M. Tesone Activity and expression of different members of the caspase family in the rat corpus luteum during pregnancy and postpartum Am J Physiol Endocrinol Metab, November 1, 2007; 293(5): E1215 - E1223. [Abstract] [Full Text] [PDF]

				P. Singh, A. Krishna, and R. Sridaran Localization of gonadotrophin-releasing hormone I, bradykinin and their receptors in the ovaries of non-mammalian vertebrates Reproduction, May 1, 2007; 133(5): 969 - 981. [Abstract] [Full Text] [PDF]

				G. Irusta, F. Parborell, and M. Tesone Inhibition of cytochrome P-450 C17 enzyme by a GnRH agonist in ovarian follicles from gonadotropin-stimulated rats Am J Physiol Endocrinol Metab, May 1, 2007; 292(5): E1456 - E1464. [Abstract] [Full Text] [PDF]

				D. M. Stocco, X. Wang, Y. Jo, and P. R. Manna Multiple Signaling Pathways Regulating Steroidogenesis and Steroidogenic Acute Regulatory Protein Expression: More Complicated than We Thought Mol. Endocrinol., November 1, 2005; 19(11): 2647 - 2659. [Abstract] [Full Text] [PDF]

				M. Tesone, R. L. Stouffer, S. M. Borman, J. D. Hennebold, and T. A. Molskness Vascular Endothelial Growth Factor (VEGF) Production by the Monkey Corpus Luteum During the Menstrual Cycle: Isoform-Selective Messenger RNA Expression In Vivo and Hypoxia-Regulated Protein Secretion In Vitro Biol Reprod, November 1, 2005; 73(5): 927 - 934. [Abstract] [Full Text] [PDF]