Insulin Sensitivity, Leptin, Adiponectin, Resistin, and Testosterone in Adult Male and Female Rats After Maternal-Neonatal Separation and Environmental Stress

Care of premature infants often requires parental and caregiver separation particularly during hypoxic and hypothermic episodes. We have established a neonatal rat model of human prematurity involving maternal-neonatal separation and hypoxia with spontaneous hypothermia prevented with external heat. Adults previously exposed to these neonatal stressors show a sex difference in the insulin and glucose response to arginine stimulation suggesting a state of insulin resistance. The current study used this cohort of adult rats to evaluate insulin resistance (Homeostatic Model Assessment of Insulin Resistance [HOMA-IR]), plasma adipokines (reflecting insulin resistance states), and testosterone. The major findings were that daily maternal-neonatal separation led to an increase in body weight and HOMA-IR in adult male and female rats and increased plasma leptin in adult male rats only; neither prior neonatal hypoxia (without or with body temperature control) nor neonatal hypothermia altered subsequent adult HOMA-IR or plasma adiponectin. Adult male-female differences in plasma leptin were lost with prior exposure to neonatal hypoxia or hypothermia; male-female differences in resistin were lost in the adults with prior neonatal hypoxia allowing spontaneous hypothermia Exposure of neonates to daily hypoxia while preventing spontaneous hypothermia led to a decrease in plasma testosterone in adult male rats. We conclude that neonatal stressors result in subsequent adult sex-dependent increases in insulin resistance and adipokines, and that our rat model of prematurity with hypoxia with the prevention of hypothermia alters adult testosterone dynamics.

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