The objective of this experiment was to determine the effect of mifepristone, a progesterone receptor antagonist, on pregnancy and secretion of steroids, pregnancy-specific protein B (PSPB) and prostaglandins at mid-pregnancy in ewes. Ninety-day pregnant ewes were ovariectomized (OVX) and treatments were initiated 72h post-OVX. Ewes received (1) vehicle, (2) prostaglandin F2α (PGF2α, 8mg/58kg/bw, i.m.) 84h post-OVX, (3) mifepristone (50mg intrajugular at 72, 84, 96, and 108h post-OVX), (4) mifepristone (50mg)+PGF2α, (5) mifepristone (100mg intrajugular at 72, 84, 96, and 108h), and (6) mifepristone (100mg)+PGF2α. Ewes treated with vehicle or PGF2α alone did not abort (P≥0.05). But, 60, 80, 60, and 100% of ewes treated with mifepristone (50mg), mifepristone (50mg)+PGF2α, mifepristone (100mg), and mifepristone (100mg)+PGF2α, respectively, aborted (P≤0.05). Profiles of progesterone, estradiol-17β, prostaglandin E (PGE), or PSPB did not differ (P≥0.05) among treatment groups. Profiles of PGF2α of treatment groups receiving mifepristone with or without PGF2α differed (P<0.05) from vehicle or PGF2α alone-treated ewes. It is concluded that progesterone actions are necessary to suppress uterine/placental secretion of PGF2α and that maintenance of critical progesterone: estradiol-17β and PGE:PGF2α ratios are necessary for maintenance of pregnancy.
|Number of pages||14|
|Journal||Prostaglandins and Other Lipid Mediators|
|State||Published - Sep 2002|
Bibliographical noteFunding Information:
The authors gratefully acknowledge the assistance of Mr. Alan Umaki and Mr. Armand Unabia, Waialee Livestock Research Farm for care, estrous detection, and mating of sheep used in these studies. The antiserum for the progesterone assay was kindly supplied by Dr. R.L. Butcher, West Virginia University; antiserum for PGF 2α was kindly provided by Dr. L. Levine, Brandeis University, Waltham, MA; and antiserum for PGE assays was kindly supplied by Dr. N. Mason, Lily Research Laboratories, Indianapolis, IN. Also the authors acknowledge the support of Mr. Bruce Robinson, Niihau Ranch. The authors also want to thank Mr. Eric Johnson, Hawaii Mega-Cor, Honolulu, HI for providing surgical supplies. The authors want to thank Mr. Wayne Toma for assistance with statistical analysis and computer graphics and Ms. Beverly Chang for typing of the manuscript.
- Prostaglandin PGF
ASJC Scopus subject areas
- Cell Biology