This Article Full Text (PDF) References 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 Add to Saved Citations Download to citation manager Request Permissions Request Reprints Add to My Marked Citations Citing Articles Citing Articles via Google Scholar Citing Articles via Scopus Google Scholar Articles by Bernardini, L. Articles by Balmaceda, J. P. Search for Related Content PubMed PubMed Citation Articles by Bernardini, L. Articles by Moretti-Rojas, I. Articles by Brush, M. Articles by Rojas, F. J. Articles by Balmaceda, J. P. Social Bookmarking                         What's this?

Status of hCG/LH Receptor and G Proteins in Human Endometrium During Artificial Cycles of Hormone Replacement Therapy

Ines Moretti-Rojas, PharmD

Michael Brush, BS

Department of Obstetrics and Gynecology, University of California, Irvine, Orange, California; Hitachi Chemical Research Center, Irvine, California

Francisco J. Rojas, PhD

Division of Reproductive Endocrinology and Infertility, Department of Obstetrics and Gynecology, University of California, Irvine, P.O. Box 14091, Orange, CA 92613-1491; Hitachi Chemical Research Center, Irvine, California

Jose P. Balmaceda, MD

Department of Obstetrics and Gynecology, University of California, Irvine, Orange, California; Hitachi Chemical Research Center, Irvine, California

Objectives: We examined the existence of hCG/LH receptors and associated GTP-binding (G) proteins in membrane fractions of nonpregnant human endometrium and investigated whether their expression is affected, in vivo, by estrogen and progesterone replacement therapy.

Methods: A pool of normal endometrial biopsy specimens (n = 5) was initially used to characterize receptors and G proteins. Subsequently, biopsy specimens (n = 22) were obtained from 11 patients undergoing evaluation cycles of hormone replacement therapy (HRT). From each patient, two specimens were collected on successive cycle days: on day 0 (last day of estrogen) and on either day 3, 6, or 9 of progesterone supplementation. Both hCG/LH receptor and G proteins were determined in membrane (10,000 x g) fractions by immunoblot analysis using specific polyclonal antibodies against synthetic fragments of hCG/LH receptor and against G proteins. Membrane fractions from rat brain and rat corpus luteum were used as controls. Proteins were loaded on the gel under reducing conditions.

Results: The receptor antibody immunoreacted with a protein of approximately 68 kd in endometrial membranes. A similar protein was detected in rat corpus luteum. The G-protein antibodies detected Gs, Gi3, Gi1/Gi2, and common beta subunits in endometrial membranes with a molecular weight of 48-42 kd, 41 kd, 40 kd, and 37 kd, respectively. Analysis of membranes obtained during HRT indicated that levels of hCG/LH receptors remained fairly constant throughout the cycle days (days 0, 3, 6, and 9). Similar results were observed for Gi1/Gi2 and Gi3. In great contrast, Gs was low at day 0 but increased with the administration of progesterone (days 3, 6, and 9).

Conclusions: Human endometrium contains both membrane-bound hCG/LH receptors and associated G proteins. During HRT, progesterone ssupplementation to estrogen therapy enhances the expression of Gs protein subunit, but not hCG/LH receptors.

Key Words: hCG/LH receptor • G proteins • human endometrium • hormone replacement therapy

Journal of the Society for Gynecologic Investigation, Vol. 2, No. 4, 630-635 (1995)
DOI: 10.1177/107155769500200409


CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    Twitter    What's this?