Testosterone replacement fails to reverse the adverse effects of streptozotocin-induced diabetes on sexual behavior in the male rat.

The ability of testosterone to reverse the adverse effects of streptozotocin-induced (STZ) diabetes on male sexual function was tested in adult male rats. Treatment with STZ (50 mg/kg) led to a significant reduction of plasma testosterone (T) levels and in the number of rats exhibiting ejaculatory behavior in a 30-minute test period. A similar reduction in T levels and ejaculatory behavior was seen in rats subjected to caloric restriction to mimic the weight loss seen in the STZ-treated rats. T-replacement (200 micrograms/day) restored T levels to those seen in control animals, but did not reverse the adverse effects of STZ on copulatory behavior. STZ-induced changes in copulatory behavior were associated with changes in hypothalamic LHRH levels and catecholamine turnover. Caloric restriction also caused endocrine and neuroendocrine changes, but they were not similar to those seen in STZ rats suggesting that these two treatments affect copulatory behavior by different mechanisms.