Uterine Glycogen Metabolism of the Rat in Early Pregnancy

Abstract

Rat uterine glycogen metabolism has been studied in the intact cycling, ovaniectomized and early pregnant rat. The uterine glycogen content and the activity levels of glycogen synthetase and glycogen phosphorylase were determined under these various endocrine states. During early pregnancy, the maximal glycogen stores achieved at estrus, decline in a consistent manner along with the enzymes of glycogen metabolism. An increase in glycogen turnover occurs, however, as indexed by the activity levels of synthetase and phosphorylase at a time period of early pregnancy coincident to the egg implantation process. These changes in uterine glycogen metabolism suggest that glycogen may play an important role in the nutritional welfare of the preimplanting embryo and may also be a limiting factor to the energy metabolism associated with egg implantation.