Biology of Reproduction, Vol 33, 1113-1119, Copyright © 1985 by Society for the Study of Reproduction

ARTICLES

Effect of pregnancy on oxytocin-induced release of prostaglandin F2 alpha in heifers

M Lafrance and AK Goff

The effect of pregnancy on the release of prostaglandin F2 alpha (PGF2 alpha) in response to oxytocin (OT) has been examined. Fourteen cyclic heifers received one intravenous injection of 1 IU OT (n = 6) or 100 IU OT (n = 8) 17, 18, or 19 days (Day 17-19) after the onset of estrus (Day 0). Five of these animals also received 100 IU OT at Days 6 and 13 to determine the effect of OT at different times of the cycle. Frequent blood samples were taken for 60 min before and for 90 min after OT injection for the measurement of 15-keto-13,14-dihydro-PGF2 alpha (PGFM) by radioimmunoassay. The experiment was then repeated using the same animals at Day 17-19 of pregnancy (confirmed by the recovery of an embryo the day after OT injection). Following the injection of 1 IU OT, plasma PGFM reached its peak within 30 min with the increase significantly lower (P less than 0.05) in pregnant (1.13 +/- 0.10-fold) than in nonpregnant animals (2.07 +/- 0.27-fold). However, because only 3 of the 6 cyclic animals showed a response to 1 IU OT, the dose was increased to 100 IU in subsequent experiments. The animals that received 100 IU at Days 6 and 13 had no significant increase in PGFM concentrations (1.18 +/- 0.05-fold and 1.01 +/- 0.04-fold, respectively). At Day 17-19 the increase in plasma PGFM reached its peak 5-15 min after 100 IU OT and the increase was significantly greater in nonpregnant (3.23 +/- 0.17-fold) than in pregnant (1.21 +/- 0.02-fold; P = 0.003) heifers. Six of 11 animals injected at Day 17-19 of the cycle showed a decrease in progesterone (P4) the day after OT administration. These data show that the release of PGF2 alpha in response to OT is suppressed in pregnant animals in vivo, suggesting an antiluteolytic role for the embryo in luteostasis.

This article has been cited by other articles:

				V. M. Portela, P. B. D. Goncalves, A. M. Veiga, E. Nicola, J. Buratini Jr., and C. A. Price Regulation of Angiotensin Type 2 Receptor in Bovine Granulosa Cells Endocrinology, October 1, 2008; 149(10): 5004 - 5011. [Abstract] [Full Text] [PDF]

				X. Zheng, C. A Price, Y. Tremblay, J. G Lussier, and P. D Carriere Role of transforming growth factor-{beta}1 in gene expression and activity of estradiol and progesterone-generating enzymes in FSH-stimulated bovine granulosa cells Reproduction, October 1, 2008; 136(4): 447 - 457. [Abstract] [Full Text] [PDF]

				J Buratini Jr., M.G.L Pinto, A.C Castilho, R.L Amorim, I.C Giometti, V.M Portela, E.S Nicola, and C.A Price Expression and Function of Fibroblast Growth Factor 10 and Its Receptor, Fibroblast Growth Factor Receptor 2B, in Bovine Follicles Biol Reprod, October 1, 2007; 77(4): 743 - 750. [Abstract] [Full Text] [PDF]

				J M Silva, M Hamel, M Sahmi, and C A Price Control of oestradiol secretion and of cytochrome P450 aromatase messenger ribonucleic acid accumulation by FSH involves different intracellular pathways in oestrogenic bovine granulosa cells in vitro. Reproduction, December 1, 2006; 132(6): 909 - 917. [Abstract] [Full Text] [PDF]

				K. R. Kieborz-Loos, H. A. Garverick, D. H. Keisler, S. A. Hamilton, B. E. Salfen, R. S. Youngquist, and M. F Smith Oxytocin-induced secretion of prostaglandin F2{alpha} in postpartum beef cows: Effects of progesterone and estradiol-17{beta} treatment J Anim Sci, July 1, 2003; 81(7): 1830 - 1836. [Abstract] [Full Text] [PDF]

				M. Bogacki, W.J. Silvia, R. Rekawiecki, and J. Kotwica Direct Inhibitory Effect of Progesterone on Oxytocin-Induced Secretion of Prostaglandin F2{alpha} from Bovine Endometrial Tissue Biol Reprod, July 1, 2002; 67(1): 184 - 188. [Abstract] [Full Text] [PDF]

				J. K. Pru, B. R. Rueda, K. J. Austin, W. W. Thatcher, A. Guzeloglu, and T. R. Hansen Interferon-Tau Suppresses Prostaglandin F2{{alpha}} Secretion Independently of the Mitogen-Activated Protein Kinase and Nuclear Factor {{kappa}} B Pathways Biol Reprod, March 1, 2001; 64(3): 965 - 973. [Abstract] [Full Text]

				Y. Miyamoto, D. J. Skarzynski, and K. Okuda Is Tumor Necrosis Factor {alpha} a Trigger for the Initiation of Endometrial Prostaglandin F2{alpha} Release at Luteolysis in Cattle? Biol Reprod, May 1, 2000; 62(5): 1109 - 1115. [Abstract] [Full Text]

				G. D. Niswender, J. L. Juengel, P. J. Silva, M. K. Rollyson, and E. W. McIntush Mechanisms Controlling the Function and Life Span of the Corpus Luteum Physiol Rev, January 1, 2000; 80(1): 1 - 29. [Abstract] [Full Text] [PDF]

				J. Manuel Silva and C. A. Price Effect of Follicle-Stimulating Hormone on Steroid Secretion and Messenger Ribonucleic Acids Encoding Cytochromes P450 Aromatase and Cholesterol Side-Chain Cleavage in Bovine Granulosa Cells In Vitro Biol Reprod, January 1, 2000; 62(1): 186 - 191. [Abstract] [Full Text]

				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]

				D.A. Douglas, A. Houde, J.H. Song, R. Farookhi, P.W. Concannon and, and B.D. Murphy Luteotropic Hormone Receptors in the Ovary of the Mink (Mustela vison) during Delayed Implantation and Early-Postimplantation Gestation Biol Reprod, July 1, 1998; 59(3): 571 - 578. [Abstract] [Full Text]