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: 69/2/390    most recent biolreprod.103.015578v1 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 My Folders Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Corbin, C.J. Articles by Conley, A.J. Search for Related Content PubMed PubMed Citation Articles by Corbin, C.J. Articles by Conley, A.J. Agricola Articles by Corbin, C.J. Articles by Conley, A.J.

Biochemical Assessment of Limits to Estrogen Synthesis in Porcine Follicles¹

Department of Population Health & Reproduction,³ School of Veterinary Medicine, University of California, Davis, California 95616 Roman L. Hruska U.S. Meat Animal Research Center,⁴ ARS, USDA, Clay Center, Nebraska 68933 Department of Pharmacology & Therapeutics,⁵ University of Maryland School of Medicine, Baltimore, Maryland 21201

Limits to estrogen production by early and late preovulatory porcine follicles were assessed by comparing enzymatic capacities for androgen (17,20-lyase) and estrogen (aromatase) synthesis in theca interna and granulosa, support of enzyme activities by the redox partner proteins NADPH-cytochrome P450 oxidoreductase (reductase) and cytochrome b₅, and tissue-specific expression and regulation of these proteins. Parameters included follicular fluid (FF) estradiol and progesterone levels, theca and granulosa aromatase and reductase activities, and theca 17,20-lyase activity. Expression of proteins responsible for these activities, aromatase (P450arom) and 17-hydroxylase/17,20-lyase (P450c17) cytochromes P450, reductase, and for the first time in ovarian tissues cytochrome b₅, were examined by Western immunoblot and immunocytochemistry. Theca and granulosa aromatase activities were as much as 100-fold lower than theca 17,20-lyase activity, but aromatase was correlated with only the log of FF estradiol. Granulosa reductase activity was twice that of the theca, and cytochrome b₅ expression was clearly identified in both the theca and granulosa layers, as was P450arom, but was not highly correlated with either 17,20-lyase or aromatase activities. Reductase expression did not change with stage of follicular development, but cytochrome b₅, P450c17, and P450arom were markedly lower in post-LH tissues. These data indicate that aromatase and not 17,20-lyase must limit porcine follicular estradiol synthesis, but this limitation is not reflected acutely in FF steroid concentrations. Neither reductase nor cytochrome b₅ appear to regulate P450 activities, but the expression of cytochrome b₅ in granulosa and theca suggests possible alternative roles for this protein in follicular development or function.

¹ This work was supported by grant USDA-NRI 98-35203-6439 (to A.J.C). J.D.V. was supported by training grant funds (ES07055) from NIEHS.

² Correspondence: Alan Conley, Department of Population Health & Reproduction, School of Veterinary Medicine, 1131 Tupper Hall, University of California, Davis, CA 95616. FAX: 530 52 4278; ajconley{at}ucdavis.edu

This article has been cited by other articles:

				D. Schams, V. Steinberg, M. Steffl, H. H D Meyer, and B. Berisha Expression and possible role of fibroblast growth factor family members in porcine antral follicles during final maturation Reproduction, July 1, 2009; 138(1): 141 - 149. [Abstract] [Full Text] [PDF]

				K Sabeur and B A Ball Characterization of NADPH oxidase 5 in equine testis and spermatozoa Reproduction, August 1, 2007; 134(2): 263 - 270. [Abstract] [Full Text] [PDF]

				E.E. At-Taras, A.J. Conley, T. Berger, and J.F. Roser Reducing Estrogen Synthesis Does Not Affect Gonadotropin Secretion in the Developing Boar Biol Reprod, January 1, 2006; 74(1): 58 - 66. [Abstract] [Full Text] [PDF]

				A. R. Caetano, R. K. Johnson, J. J. Ford, and D. Pomp Microarray Profiling for Differential Gene Expression in Ovaries and Ovarian Follicles of Pigs Selected for Increased Ovulation Rate Genetics, November 1, 2004; 168(3): 1529 - 1537. [Abstract] [Full Text] [PDF]

				J. W. Newman, J. E. Stok, J. D. Vidal, C. J. Corbin, Q. Huang, B. D. Hammock, and A. J. Conley Cytochrome P450-Dependent Lipid Metabolism in Preovulatory Follicles Endocrinology, November 1, 2004; 145(11): 5097 - 5105. [Abstract] [Full Text] [PDF]

				C. J. Corbin, S. M. Mapes, J. Marcos, C. H. Shackleton, D. Morrow, S. Safe, T. Wise, J. J. Ford, and A. J. Conley Paralogues of Porcine Aromatase Cytochrome P450: A Novel Hydroxylase Activity Is Associated with the Survival of a Duplicated Gene Endocrinology, May 1, 2004; 145(5): 2157 - 2164. [Abstract] [Full Text] [PDF]