Effect of ovariectomy on plasma levels of progesterone, free and conjugated estrone in pregnant sheep

Abstract

Progesterone, free and conjugated estrone were determined in peripheral plasma from ovariectomized and control pregnant ewes in order to observe the ovary contribution to these hormonal levels. Progesterone levels during pregnancy were lower in the ovariectomized ewes than in control, although the differences were significant only until the 120th day of pregnancy. From the 130th day to the 3rd-5th day prepartum, an increase in the hormone levels was observed in both groups of ewes indicating a placentary contribution. Very similar patterns were followed by the free and conjugated estrone concentrations, their levels not being significantly different in either group. Production of conjugated estrone both preceded and reached higher values than that of free estrone. Both hormones showed an abrupt increase in concentration two days before the parturition, decreasing after that. Parturition mechanisms, foetus viability and the length of pregnancy were not affected by ovariectomy.