Growth Hormone Administration Controls Body Composition Associated with Changes of Thermogenesis in Obese KK-Ay Mice

ABSTRACT

We investigate the effects of continuous human growth hormone (GH) therapy in young obese mice on thermogenesis. Female KK-Ay obese mice (n=10) were injected subcutaneously with GH (3.5 mg/kg/day) for 30 days from 42 days old. As a control, physiological saline was administered (n=10). At the terminal point (71 days old), GH administration affected linear growth, and the Lee obesity index (3 square root body weight/nasoanal length X 1000) was significantly decreased. Rates of inguinal and perimetric white adipose pads per body weight also decreased. Free fatty acid levels decreased, while plasma insulin concentrations and homeostasis model assessment insulin resistance were increased (P<0.01). Plasma insulin-like growth factor I(IGF-1) levels markedly rose (P<0.00001). Uncoupling protein1 (UCP1) and UCP3 mRNA expressions in brown adipose tissue were inhibited (P<0.05). Continuous GH therapy changed obese body composition toward lean, however, the consequence could be the negative regulation of thermogenesis.