Endocrinology, Vol 99, 1107-1114, Copyright © 1976 by Endocrine Society

ARTICLES

Oxytocin-stimulated release of prostaglandin F2alpha from ovine endometrium in vitro: correlation with estrous cycle and oxytocin- receptor binding

JS Roberts, JA McCracken, JE Gavagan and MS Soloff

Endometrial and myometrial tissues, obtained from Merino ewes on 5 different days of the estrous cycle, were incubated at 37 C in 30 ml of gassed (95% O2:5% CO2) Krebs-bicarbonate buffer containing, 0, 10, 100 or 1,000 muU/ml oxytocin. Aliquots of the medium were removed at 10 min intervals and examined for prostaglandin F2alpha (PGF2alpha) content by radioimmunoassay. Fresh-frozen (-70 C) samples of endometrial and myometrial tissue were homogenized in Tyrode's solution. Particulate fractions from each tissue, sedimenting between 1,000 X g for 10 min and 165,000 X g for 30 min, were prepared and assayed for [3H]oxytocin- binding activity. Endometrium incubated in vitro released PGF2alpha spontaneously and oxytocin enhanced this release in a dose-dependent manner. The degree of enhancement with low doses of oxytocin appeared to increase as estrus approached, reaching a maximum on the day of estrus. High-affinity binding sites (Kd = 5 to 7 X 10(-10) M) were found in both myometrium and endometrium. The number of high-affinity sites rose to a peak at estrus in both tissues but the binding capacity of endometrium was twice that of the myometrium at this time. Although both tissues released PGF2alpha during incubation, oxytocin enhanced release from endometrial tissue only. The results suggest that (i) the endometrium is a target for oxytocin, (ii) synthesis of PGF2alpha by the uterus may involve interaction between oxytocin and its endometrial receptors and (iii) ovarian steroids may influence uterine PG synthesis by regulating the availability of these receptors.

This article has been cited by other articles:

				X H Zhang, S Filippi, L Vignozzi, A Morelli, R Mancina, M Luconi, S Donati, M Marini, G B Vannelli, G Forti, et al. Identification, localization and functional in vitro and in vivo activity of oxytocin receptor in the rat penis J. Endocrinol., March 1, 2005; 184(3): 567 - 576. [Abstract] [Full Text] [PDF]

				O. Chami, G. Evans, and C. O'Neill Components of a platelet-activating factor-signaling loop are assembled in the ovine endometrium late in the estrous cycle Am J Physiol Endocrinol Metab, August 1, 2004; 287(2): E233 - E240. [Abstract] [Full Text] [PDF]

				O.N. Richter, K. Kubler, J. Schmolling, M. Kupka, J. Reinsberg, U. Ulrich, H. van derVen, E. Wardelmann, and K. van derVen Oxytocin receptor gene expression of estrogen-stimulated human myometrium in extracorporeally perfused non-pregnant uteri Mol. Hum. Reprod., May 1, 2004; 10(5): 339 - 346. [Abstract] [Full Text] [PDF]

				P. D. Burns, J. O.B. Mendes Jr., R. S. Yemm, C. M. Clay, S. E. Nelson, S. H. Hayes, and W. J. Silvia Cellular Mechanisms by Which Oxytocin Mediates Ovine Endometrial Prostaglandin F2{alpha} Synthesis: Role of Gi Proteins and Mitogen-Activated Protein Kinases Biol Reprod, October 1, 2001; 65(4): 1150 - 1155. [Abstract] [Full Text] [PDF]

				G. Gimpl and F. Fahrenholz The Oxytocin Receptor System: Structure, Function, and Regulation Physiol Rev, April 1, 2001; 81(2): 629 - 683. [Abstract] [Full Text] [PDF]

				S.J. Filley, H.A. Turner, and F. Stormshak Prostaglandin F2{alpha} Concentrations, Fatty Acid Profiles, and Fertility in Lipid-Infused Postpartum Beef Heifers Biol Reprod, November 1, 1999; 61(5): 1317 - 1323. [Abstract] [Full Text]

				S. Hoare, J. A. Copland, T. G. Wood, Y.-J. Jeng, M. G. Izban, and M. S. Soloff Identification of a GABP{alpha}/{beta} Binding Site Involved in the Induction of Oxytocin Receptor Gene Expression in Human Breast Cells. Potentiation by c-Fos/c-Jun Endocrinology, May 1, 1999; 140(5): 2268 - 2279. [Abstract] [Full Text]

				J. A. McCracken, E. E. Custer, and J. C. Lamsa Luteolysis: A Neuroendocrine-Mediated Event Physiol Rev, April 1, 1999; 79(2): 263 - 323. [Abstract] [Full Text] [PDF]

				C. W. Xiao, B. D. Murphy, J. Sirois, and A. K. Goff Down-Regulation of Oxytocin-Induced Cyclooxygenase-2 and Prostaglandin F Synthase Expression by Interferon-{tau} in Bovine Endometrial Cells Biol Reprod, March 1, 1999; 60(3): 656 - 663. [Abstract] [Full Text]

				M. Baguma-Nibasheka and P. W. Nathanielsz In Vivo Administration of Nimesulide, a Selective PGHS-2 Inhibitor, Increases In Vitro Myometrial Sensitivity to Prostaglandins While Lowering Sensitivity to Oxytocin Reproductive Sciences, November 1, 1998; 5(6): 296 - 299. [Abstract] [PDF]

				E. Asselin, P. Drolet, and M. A. Fortier In Vitro Response to Oxytocin and Interferon-Tau in Bovine Endometrial Cells from Caruncular and Inter-Caruncular Areas Biol Reprod, August 1, 1998; 59(2): 241 - 247. [Abstract] [Full Text]

				T. M. Hazzard, K. L. Pinckard, and F. Stormshak Impact of Chronic Treatment of Ewes with Estradiol-17ss or Progesterone on Oxytocin Receptor Gene Transcription and Ovarian Oxytocin Secretion Biol Reprod, July 1, 1998; 59(1): 105 - 110. [Abstract] [Full Text]

				E. Asselin, P. Drolet, and M. A. Fortier Cellular Mechanisms Involved during Oxytocin-Induced Prostaglandin F2{alpha} Production in Endometrial Epithelial Cells in Vitro: Role of Cyclooxygenase-2 Endocrinology, November 1, 1997; 138(11): 4798 - 4805. [Abstract] [Full Text] [PDF]

				A. Fuchs, F Fuchs, P Husslein, M. Soloff, and M. Fernstrom Oxytocin receptors and human parturition: a dual role for oxytocin in the initiation of labor Science, March 12, 1982; 215(4538): 1396 - 1398. [Abstract] [PDF]

				M. Soloff, M Alexandrova, and M. Fernstrom Oxytocin receptors: triggers for parturition and lactation? Science, June 22, 1979; 204(4399): 1313 - 1315. [Abstract] [PDF]