SEASONAL CHANGES IN IN VITRO PRODUCTION OF TESTICULAR ANDROGENS BY COBRA (NAJA NAJA LINN)

The seasonal variations in androgen production by the cobra testis have been investigated in vitro using progesterone-4-C14 as a precursor. Testosterone and androstenedione are the major testicular androgens and their production shows quantitative, rather than qualitative, changes throughout the year. Testosterone synthesis is low during the May-August period of spermatogenetic inactivity, but rises rapidly during the period of spermatogenetic recrudescence in late August and early September, and is maintained at a high level, apart from a temporary suppression during the hibernation period, until the end of the breeding season in early May. Deoxycorticosterone and aldosterone are also synthesized by the cobra testis in vitro. The biochemical results closely parallel the seasonal histochemical changes, and support the view that gradual discharge of Leydig cell cytoplasmic lipid inclusions reflects an increase in androgen secretory activity, while conversely, a profuse accumulation of strongly cholesterol-positive lipid in the Leydig cells indicates reduced androgen secretory activity. The possibility is discussed that the almost synchronous recovery of androgen production rate and of recrudescence of spermatogenesis might be interrelated. © 1969.