Ovarian Control of Certain Enzymes in the Mammary Gland of the Lactating Rat

Abstract

The effects of ovariectomy on the activities of glucose-6-phosphate dehydrogenase (EC 1.1.1.49), 6-phos-phogluconate dehydrogenase (EC 1.1.1.44), and NADP+-malic dehydrogenase (EC l,1.1.40)in the rat mammary gland during lactation were evaluated. The effects of estradiol and progesterone were also assessed. Ovariectomy reduced the activities of these enzymes which were found to be normally at their highest activity on the 15th day of lactation. Ovariectomy prevented the characteristic decrease in the enzyme activities following their peak at the 15th day. Estradiol was found to elevate the total activity of all 3 enzymes in the mammary glands of ovariectomized rats in their 10th day of lactation. Progesterone increased the activities of all 3 enzymes in this organ, but the increase was generally less than that caused by estradiol.