NADPH generating enzymes in Leydig cells from diabetic rats.

Impaired testosterone biosynthesis in Leydig cells from streptozotocin treated rats is correlated with the reduced activity of glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase and isocitrate dehydrogenase. The results shown demonstrate that in the diabetic state the activity of these enzymes is reduced by almost 50 to 59% from normal levels. Insulin treatment restored their activities to normal levels. The diminished supply of NADPH in diabetic interstitial tissue is not the unique factor in the control of steroidogenesis, since the availability of large amounts of exogenous NADPH in the incubations of Leydig cell did not reduce the differences in testosterone synthesis observed when compared with normal cells.