Endocrinology, Vol 106, 736-738, Copyright © 1980 by Endocrine Society

ARTICLES

Oxytocin receptors and parturition. II. Concentrations of receptors for oxytocin and estrogen in the gravid and nongravid uterus at term

M Alexandrova and MS Soloff

It has been postulated that intrauterine volume plays a role in the timing of parturition. In previous studies we found that the onset of parturition in the rat was associated with marked increases in the concentrations of receptors for estrogen and oxytocin in the myometrium. To determine the effects of intrauterine volume on the concentrations of these myometrial receptors, we compared receptor levels in gravid and nongravid uterine horns from unilaterally pregnant rats at or near the time of parturition. Myometria from gravid horns contained substantially greater concentrations of DNA and protein per horn than did myometria from the contralateral nongravid horns. The amounts of receptors per horn for estrogen in the nuclear and cytosol fractions and for oxytocin were 7.5, 5.2, and 4.5 times greater, respectively, in myometria from gravid horns. However, the concentration of receptors per cell was the same in gravid and nongravid horns at or near parturition. These results suggest that uterine stretch causes hyperplasia and hypertrophy of the myometrium, indicative of more DNA and protein per gravid horn than nongravid horn. The sharp rise in concentration per cell of receptors for estrogen and oxytocin occurring about the time of labor, however, appears to be induced by hormonal and not physical factors.

This article has been cited by other articles:

				A. Dalrymple, K. Mahn, L. Poston, E. Songu-Mize, and R.M. Tribe Mechanical stretch regulates TRPC expression and calcium entry in human myometrial smooth muscle cells Mol. Hum. Reprod., March 1, 2007; 13(3): 171 - 179*. [Abstract] [Full Text] [PDF]

				J. G. Ninomiya-Alarcon, R. Hudson, G. Reyes-Guerrero, B. Barrera-Mera, and R. Guevara-Guzman Effect of photoperiod on the mechanical response of the pregnant rabbit uterus to oxytocin Am J Physiol Regulatory Integrative Comp Physiol, July 1, 2004; 287(1): R174 - R180. [Abstract] [Full Text] [PDF]

				V. Simon, M.-T. Robin, C. Legrand, and J. Cohen-Tannoudji Endogenous G Protein-Coupled Receptor Kinase 6 Triggers Homologous {beta}-Adrenergic Receptor Desensitization in Primary Uterine Smooth Muscle Cells Endocrinology, July 1, 2003; 144(7): 3058 - 3066. [Abstract] [Full Text] [PDF]

				A. L. Siebel, H. M. Gehring, and L. J. Parry Effects of Fetectomy on Oxytocin Receptors in the Myometrium of the Tammar Wallaby Biol Reprod, October 1, 2002; 67(4): 1242 - 1249. [Abstract] [Full Text] [PDF]

				A. L. Siebel, H. M. Gehring, C. D. Nave, R. A.D. Bathgate, C. E. Borchers, and L. J. Parry Up-Regulation of Mesotocin Receptors in the Tammar Wallaby Myometrium Is Pregnancy-Specific and Independent of Estrogen Biol Reprod, May 1, 2002; 66(5): 1237 - 1243. [Abstract] [Full Text]

				D. Minjarez, V. Konda, and R. A. Word Regulation of Uterine 5{alpha}-Reductase Type 1 in Mice Biol Reprod, November 1, 2001; 65(5): 1378 - 1382. [Abstract] [Full Text] [PDF]

				W. X. Wu, X. H. Ma, T. Yoshizato, N. Shinozuka, and P. W. Nathanielsz Differential Expression of Myometrial Oxytocin Receptor and Prostaglandin H Synthase 2, But Not Estrogen Receptor {alpha} and Heat Shock Protein 90 Messenger Ribonucleic Acid in the Gravid Horn and Nongravid Horn in Sheep during Betamethasone-Induced Labor Endocrinology, December 1, 1999; 140(12): 5712 - 5718. [Abstract] [Full Text]

				C.-W. Ou, Z.-Q. Chen, S. Qi, and S. J. Lye Increased Expression of the Rat Myometrial Oxytocin Receptor Messenger Ribonucleic Acid during Labor Requires Both Mechanical and Hormonal Signals Biol Reprod, November 1, 1998; 59(5): 1055 - 1061. [Abstract] [Full Text]

				C.-W. Ou, A. Orsino, and S. J. Lye Expression of Connexin-43 and Connexin-26 in the Rat Myometrium during Pregnancy and Labor Is Differentially Regulated by Mechanical and Hormonal Signals Endocrinology, December 1, 1997; 138(12): 5398 - 5407. [Abstract] [Full Text] [PDF]