Endocrinology, Vol 130, 3159-3166, Copyright © 1992 by Endocrine Society

ARTICLES

Influence of ovarian steroids on relaxin-induced uterine growth in ovariectomized gilts

JA Hall, TC Cantley, JM Galvin, BN Day and RV Anthony
Department of Animal Sciences, University of Missouri, Columbia 65211.

This study examined the influence of ovarian steroids on the uterotropic actions of relaxin (RLX) in ovariectomized prepubertal gilts. Ovariectomized gilts received (im) corn oil (CO), estradiol benzoate (EB), or EB and progesterone (P) for 0-16 days. Steroid administration was patterned to approximate the plasma concentrations of endogenous ovarian steroids observed during 1) the follicular phase (EB), 2) luteal phase (EB+P), and 3) early pregnancy (EB+P+EB). Half of each group also received PBS or 0.5 mg RLX every 6 h for 54 h, coinciding with the final 2 days of the experimental period. After hysterectomy, uterine tissues were analyzed for water, dry matter, protein, DNA, glycosaminoglycans (GAGs), and collagen contents. Administration of EB or P increased uterine weight 5- to 6-fold, but no differences were observed between EB+P- and EB+P+EB-treated gilts. Cotreatment with RLX enhanced steroid-induced uterine growth 40-70%, and RLX stimulated growth in CO- and EB+CO control gilts 2- to 3-fold. The water content of uterine tissues was greater in EB-, EB+P-, and EB+P+EB-treated gilts than in their respective controls, and this response was augmented by RLX in all treatment groups. Administration of steroids stimulated a 4- to 5-fold increase in uterine dry weight compared to that in controls, with responses not differing between EB+P- and EB+P+EB-treated gilts. In all groups, RLX increased uterine dry weight. Protein and DNA contents of uterine tissue increased with steroid treatment, but neither variable differed between EB+P- and EB+P+EB-treated gilts. Administration of RLX, alone or in combination with steroids, increased protein and DNA contents of uterine tissues. The tissue content of GAGs increased in response to steroids, and coadministration of RLX did not alter this response. Although the uterine tissue concentration of collagen was reduced in steroid- and RLX-treated gilts, the collagen content of the uterus was not affected by the various treatments. The results of this study indicate that RLX is a potent stimulator of uterine growth under a variety of steroidal environments. RLX- or steroid-induced uterine growth was manifest by increased water, dry matter, protein, and DNA and GAG contents, but the uterine content of collagen was not affected. The overall growth- promoting effects of EB and the stimulation of DNA accretion by RLX were not observed when gilts were cotreated with P.(ABSTRACT TRUNCATED AT 400 WORDS)

This article has been cited by other articles:

				W. Yan, A. A. Wiley, R. A. D. Bathgate, A.-L. Frankshun, S. Lasano, B. D. Crean, B. G. Steinetz, C. A. Bagnell, and F. F. Bartol Expression of LGR7 and LGR8 by Neonatal Porcine Uterine Tissues and Transmission of Milk-Borne Relaxin into the Neonatal Circulation by Suckling Endocrinology, September 1, 2006; 147(9): 4303 - 4310. [Abstract] [Full Text] [PDF]

				C. C. Smith and L. L. McMahon Estradiol-Induced Increase in the Magnitude of Long-Term Potentiation Is Prevented by Blocking NR2B-Containing Receptors. J. Neurosci., August 15, 2006; 26(33): 8517 - 8522. [Abstract] [Full Text] [PDF]

				W. Yan, P. L Ryan, F. F Bartol, and C. A Bagnell Uterotrophic effects of relaxin related to age and estrogen receptor activation in neonatal pigs. Reproduction, May 1, 2006; 131(5): 943 - 950. [Abstract] [Full Text] [PDF]

				J. A. Ford Jr., S. G. Clark, E. M. Walters, M. B. Wheeler, and W. L. Hurley Estrogenic effects of genistein on reproductive tissues of ovariectomized gilts J Anim Sci, April 1, 2006; 84(4): 834 - 842. [Abstract] [Full Text] [PDF]

				C. C. Smith and L. L. McMahon Estrogen-Induced Increase in the Magnitude of Long-Term Potentiation Occurs Only When the Ratio of NMDA Transmission to AMPA Transmission Is Increased J. Neurosci., August 24, 2005; 25(34): 7780 - 7791. [Abstract] [Full Text] [PDF]

				O. D. Sherwood Relaxin's Physiological Roles and Other Diverse Actions Endocr. Rev., April 1, 2004; 25(2): 205 - 234. [Abstract] [Full Text] [PDF]

				L. Zhao, C. S. Samuel, G. W. Tregear, F. Beck, and E. M. Wintour Collagen Studies in Late Pregnant Relaxin Null Mice Biol Reprod, March 1, 2000; 63(3): 697 - 703. [Abstract] [Full Text]

				K. M. Ohleth and C. A. Bagnell Relaxin Secretion and Gene Expression in Porcine Granulosa and Theca Cells Are Stimulated during In Vitro Luteinization Biol Reprod, February 1, 1999; 60(2): 499 - 507. [Abstract] [Full Text] [PDF]

				K. M. Ohleth, J. A. Lenhart, P. L. Ryan, S. V. Radecki, and C. A. Bagnell Relaxin Increases Insulin-Like Growth Factors (IGFs) and IGF-Binding Proteins of the Pig Uterus in Vivo Endocrinology, September 1, 1997; 138(9): 3652 - 3658. [Abstract] [Full Text] [PDF]

				G. Min, M. G. Hartzog, R. L. Jennings, R. J. Winn, and O. D. Sherwood Evidence That Endogenous Relaxin Promotes Growth of the Vagina and Uterus during Pregnancy in Gilts Endocrinology, February 1, 1997; 138(2): 560 - 565. [Abstract] [Full Text] [PDF]