Cytochemistry of oxidative enzyme systems in the Leydig cells of the rat testis and their functional significance.

The Leydig cells of adult rat testis were demonstrated to exhibit activities of diphosphopyridine and triphosphopyridine nucleotide diaphorases and succinic, lactic, glutamic, α-glycerophosphate, β-hydroxybutyrate and steroid-3β-ol dehydrogenases. These enzyme activities were identified even in fetal Leydig cells, where they became visible simultaneously as the cells became morphologically identifiable. The functional significance of the oxidative enzyme systems of the Leydig cells was studied in hypophysectomized and gonadotrophin treated animals; rats were also fasted or given testosterone treatment. β-Hydroxybutyrate dehydrogenase and steroid-3β-ol dehydrogenase were found to be sensitive to the experimental treatments. Hyphophysectomy caused a complete inhibition of the former and greatly depressed the activity of the latter enzyme. Inanition and testosterone also caused a marked decrease in the activity of the 2 enzymes; on the other hand, gonadotrophin had a pronounced stimulating influence on their...