Endocrinology Vol. 140, No. 5 2426-2429
Copyright © 1999 by The Endocrine Society
Relaxin Stimulates Uterine Edema via Activation of Estrogen Receptors: Blockade of its Effects Using ICI 182,789, a Specific Estrogen Receptor Antagonist
Suresh B. Pillai,
L. Christie Rockwell,
O. D. Sherwood and
Robert D. Koos
Department of Physiology (S.B.P., L.C.R., R.D.K.), University of
Maryland School of Medicine, Baltimore, Maryland 21201; and Department
of Molecular and Integrative Physiology and College of Medicine
(O.D.S.), University of Illinois, Urbana, Illinois 61801
Address all correspondence and requests for reprints to Robert D. Koos, Ph.D., University of Maryland Medical School, Department of Physiology, 655 West Baltimore Street, Baltimore, Maryland 21201-1559.
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Abstract
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Relaxin’s ability to stimulate uterine growth is well established. The
mechanisms by which relaxin exerts this effect, however, remain
unclear. In light of previous work demonstrating peptide growth factor
activation of estrogen receptors (ERs), the present study was conducted
to determine if relaxin similarly stimulates ERs. Twenty-five day-old
female Sprague-Dawley rats were bilaterally ovariectomized and treated
with estradiol or porcine relaxin alone or in combination with the ER
antagonist ICI 182,780. Following treatment with 17ß-estradiol or
relaxin alone, the uterine weight/body weight ratio (UtW/BW) increaased
significantly over control values (+98% and +77%, respectively, p
< 0.0003). Pre-treatment of animals with ICI 182,780 (3 µg/g BW)
prior to either estradiol or relaxin treatment completely inhibited the
hormone-induced increases in uterine weight (p < 0.0005). ICI 182,780
alone had no significant effect. Histological analysis of uterine
cross-sections revealed that the edema present in the endometrium of
animals treated with estradiol or relaxin alone was completely absent
in the uteri of animals pre-treated with ICI 182,780. These data
indicate that relaxin-induced uterine edema and growth is mediated by
ERs.
Received January 6, 1999.
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