The effect of hypoxia on plasma leptin and insulin in newborn and juvenile rats

Hypoxia leads to a decrease in food intake and attenuated weight gain in rats. The purpose of this study was to measure plasma leptin and insulin in young rats exposed to hypoxia for 7 d as compared to a normoxic control group of the same age. One group was exposed from birth to 7 d of age; the other was exposed from 28 to 35 d of age (weaned at 21 d of age). As expected, body weight was significantly lower in rats of either age exposed to hypoxia for 7 d. Plasma leptin was significantly lower in hypoxic (2.0±0.2 ng/mL; n=41) compared with normoxic (2.6±0.3 ng/mL; n=30) 7-d-old rats. Plasma leptin was also significantly lower in hypoxic (1.1±0.1 ng/mL; n=20) as compared to normoxic (1.5±0.1 ng/mL; n=20) 35-d-old rats. Seven-day-old rats exposed to hypoxia demonstrated significant increases in plasma glucose and insulin whereas 35-d-old rats exhibited a decrease inboth variables. We conclude that exposure to hypoxia for 7 d leads to a decrease in body weight and plasma leptin in infant and juvenile rats. The decrease in leptin may be an attempt to reverse hypoxia-induced anorexia.