title: The influence of progesterone-induced proteins on glucose metabolism in early equine embryos.
abstract: The influence of different maternal plasma progesterone concentrations on embryonic glucose metabolism was studied. Uterine flushes were obtained after treating ovariectomized mares (n = 3) with 0 (control), 100 or 200 mg progesterone daily for 7 d. A group of progesterone-induced proteins (PIP) of Mr approximately 20,000 were identified in flushes from progesterone treatments by SDS-PAGE but were not observed in control flushes. Progesterone-induced proteins were removed from half the pooled flush in each treatment group by Sepharose blue CL-6B. In a 3 x 2 factorial (progesterone treatments, progesterone-induced proteins) experiment, 6 groups of Day 7 equine embryos (n = 6 per group) were incubated in culture media (MEM:DPBS; 1:3) containing radioactively-labeled glucose. Contributions of the Embden-Meyerhof pathway (EMP) and the pentose-phosphate pathway (PPP) to the total metabolism of glucose in early equine embryos were assessed separately. In the 200 mg progesterone treatment group, the presence of progesterone-induced proteins in the culture medium resulted in a 4-to 5-fold increase in the activities of the Embden-Meyerhof pathway and the pentose-phosphate pathway. These results lead to the following conclusions: 1)Addition of progesterone-induced uterine proteins from mares with high levels of circulating progesterone enhance the metabolic activities of the Embden-Meyerhof pathway and the pentose-phosphate pathway in Day 7.5 equine embryos in culture. 2)Uterine secretion of progesterone-induced proteins which is quantitatively and/or qualitatively adequate to modify embryonic glucose metabolism in vitro is dependent on a minimal concentration of maternal plasma progesterone.
authors.affiliation: Department of Clinical Studies, Royal Veterinary and Agricultural University, 1870 Frederiksberg C, Denmark.
authors.forename: I
authors.initials: I
authors.lastname: Brück
authors.forename: G A
authors.initials: GA
authors.lastname: Anderson
authors.forename: J H
authors.initials: JH
authors.lastname: Hyland