Dexamethasone and oxytocin effects on rat Leydig cells--morphological and enzyme-histochemical characteristics

In the present study the fine structure of rat Leydig cells was examined by electron microscopy. Oxytocin and dexamethasone induced changes in the activities of 3beta hydroxysteroid dehydrogenase, NADH2 cytochrome-C-reductase and glucose-6-phosphate dehydrogenase in these cells were studied in an in vivo experiment. Two groups of male Wistar rats were used to test the effects of oxytocin--rats from group I received a single injection of oxytocin; rats from group II were given a 10-day course of oxytocin. Pregnant female rats were injected with dexamethasone on day 17 and 18 post conception. The testes of 19 and 20-day old embryos were removed. It was established that both short and long term courses of oxytocin increased the activities of the above-mentioned enzymes. On the contrary, prenatal administration of dexamethasone decreased enzymatic activity in Leydig cells. Electron microscopy revealed clusters of fetal Leydig cells. Our results indicated the role of oxytocin in the local regulation of steroidogenesis and the importance of glucocorticoids in the differentiation and activity of Leydig cells.