Testosterone is protective against impaired glucose metabolism in male intrauterine growth-restricted offspring

Placental insufficiency alters the intrauterine environment leading to increased risk for chronic disease including impaired glucose metabolism in low birth weight infants. Using a rat model of low birth weight, we previously reported that placental insufficiency induces a significant increase in circulating testosterone in male intrauterine growth-restricted offspring (mIUGR) in early adulthood that is lost by 12 months of age. Numerous studies indicate testosterone has a positive effect on glucose metabolism in men. Female growth-restricted littermates exhibit glucose intolerance at 6 months of age. Thus, the aim of this paper was to determine whether mIUGR develop impaired glucose metabolism, and whether a decrease in elevated testosterone levels plays a role in its onset. Male growth-restricted offspring were studied at 6 and 12 months of age. No impairment in glucose tolerance was observed at 6 months of age when mIUGR exhibited a 2-fold higher testosterone level compared to age-matched control. Fasting blood glucose was significantly higher and glucose tolerance was impaired with a significant decrease in circulating testosterone in mIUGR at 12 compared with 6 months of age. Castration did not additionally impair fasting blood glucose or glucose tolerance in mIUGR at 12 months of age, but fasting blood glucose was significantly elevated in castrated controls. Restoration of elevated testosterone levels significantly reduced fasting blood glucose and improved glucose tolerance in mIUGR. Thus, our findings suggest that the endogenous increase in circulating testosterone in mIUGR is protective against impaired glucose homeostasis.