Induction of Malate Dehydrogenase by Oestradiol-17β in the Human Endometrium

HISTOCHEMICAL and biochemical investigations of the human endometrium have revealed variations in the activity of a number of enzymes throughout the normal menstrual cycle1–3. Marked differences in the concentration and localization of enzymes have been found between endometrial gland cells and stromal cells. It is commonly assumed that these variations in enzyme activity are mediated by oestrogens and progesterone. I thought that a more detailed knowledge of hormone action at a cellular level might be obtained by combining organ culture of human endometrium with quantitative histochemical methods. Maurer has, for example, recently demonstrated the value of organ culture techniques for the study of the effects of steroid sex hormones on target tissues in animals4. By the combined techniques I have now detected an increase in malate dehydrogenase activity in the human endometrium stimulated in vitro by oestradiol-17β. The increase in enzyme activity occurs mainly in the cells of the endometrial glands and is suppressed by actinomycin D and I think that it is due to the formation of new enzyme.