The effect of estrogen on the activity of glucose phosphorylating enzymes in the rat uterus

Abstract

Immature rat uterus contains a higher concentration of hexokinase (low km enzyme) than immature rat liver. Unlike liver, uterine tissue does not have a high km enzyme (glucokinase). Uterine hexokinase activity shows a significant and steady increase from 8–24 hours after estradiol treatment This increased activity is evident when expressed in terms of tissue wet weight, mg. of protein, or on a per uterus basis. These different bases are necessary for activity measurements since estradiol also stimulates growth, water inhibition, and protein synthesis. Concurrent measurements of glucose-6-phosphate dehydrogenase activity in uterine homogenates indicate that this enzyme also increases in activity with a time course nearly identical to hexokinase. The increased activity of these two enzymes occurs simultaneously with a general increase in total uterine protein during this time period. Perhaps de novo synthesis of these enzymes is part of the physiological response to estradiol. However, the delayed appearance of increased activity would seem to exclude these enzymes as being responsible for early increase in uterine glucose metabolism which occur within 1–2 hours after estradiol treatment.