0021-972X/91/7206-1359$03.00/0 Journal of Clinical Endocrinology and Metabolism Copyright © 1991 by The Endocrine Society

Vol. 72, No. 6 Printed in U.S.A.

Ovarian Control of Pituitary Hormone Secretion in Early Human Pregnancy* A. M. EMMI, J. SKURNICK, L. T. GOLDSMITH, C. L. GAGLIARDI, C. L. SCHMIDT, D. KLEINBERG, AND G. WEISS Department of Obstetrics and Gynecobgy, and Preventive Medicine and Community Health (J.S.), University of Medicine and Dentistry-New Jersey Medical School, Newark, New Jersey 07103; and the Department of Medicine, Veterans Administration Medical Center, and New York University Medical Center (D.K.), New York, New York 10016

ABSTRACT. To determine the influence of ovarian relaxin on the secretion of pituitary GH and PRL in vivo, we evaluated circulating serum hormone levels in 17 pregnant patients with functional corpora lutea (group I) and compared them to levels in 10 patients with premature ovarian failure (POF; group II) who became pregnant with egg donation and did not have corpora lutea. Group II patients had exogenous hormonal support. Serum relaxin (RLX), GH, PRL, estradiol (E2), and progesterone levels were measured weekly by RIA from weeks 4-8 of pregnancy. Analysis of variance and covariance were used to determine hormonal relationships. Serum RLX was present in the natural pregnancy group, with a mean of 1.94 Mg/L over the study period. Serum RLX was undetectable in the POF patients

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ELAXIN (RLX) is an ovarian hormone produced by the corpus luteum (CL) of pregnancy. It has many effects on the reproductive tract. Recent data have suggested that RLX may also act within the central nervous system. Human RLX has been shown to increase both intracellular cAMP levels and dose-dependent PRL secretion in cultured female rat anterior pituitary cells (1, 2). cAMP is a known inducer of rat PRL gene transcription (3). Furthermore, somatostatin and dopamine have been shown to prevent the RLX-stimulated increase in cAMP, suggesting a possible effect of RLX on somatotrophs as well (1). Subsequent investigations of possible central effects of RLX were extended to other animal species. The exogenous administration of human RLX to rhesus monkeys in the midluteal phase produced an increase in serum PRL and GH concentrations (4). These data led us to postulate that a long loop feedback between luteal RLX secretion and pituitary PRL and Received October 11,1991. Address all correspondence and requests for reprints to: Gerson Weiss, M.D., Department of Obstetrics and Gynecology, University of Medicine and Dentistry-New Jersey Medical School, E-506,185 South Orange Avenue, Newark, New Jersey 07103. * This work was supported by NIH Grant HD-22338.

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Ovarian control of pituitary hormone secretion in early human pregnancy.

To determine the influence of ovarian relaxin on the secretion of pituitary GH and PRL in vivo, we evaluated circulating serum hormone levels in 17 pr...
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