An extra-pancreatic direct effect of streptozotocin on the hypothalamo-hypophyseal-testicular axis in the rat.

Streptozotocin induced diabetes mellitus in 4 out of 6 male rats. On the other hand, all 6 drug-injected animals had decreased serum testosterone values. The Leydig cells from 6 control rats and all streptozotocin-injected animals were characterized by moderate numbers of mitochondria, few lipid droplets, and an abundance of smooth surfaced endoplasmic reticulum. Quantitative analysis of numbers of mitochondria and lipid droplets revealed no differences between control and streptozotocin-injected animals. However, there were smaller mitochondria, larger lipid droplets and a trend toward fewer cells with dilated profiles of smooth endoplasmic reticulum in all drug injected animals. These cytological and biochemical findings suggest that diabetes per se had little direct effect on Leydig cell function. However, taken together with previous studies, these observations suggest that streptozotocin may directly affect the hypothalamo-pituitary-testicular axis possibly at the level of LHRH-secreting neurons of the hypothalamus.