Growth hormone treatment reduces total body fat accumulation in Zucker obese rats

Lean and obeze Zucker rats were injected daily intraperitoneally with high doses (5-10 mg/kg) of human growth hormone (GH) for 3 weeks. In the obese rats after GH treatment, carcass lipid was decreased by 50 percent, and bone weight increased to levels of lean controls. During the last two weeks of GH treatment, food intake was increased in lean rats and not significantly affected in obese rats. Loss of body weight in obese animals was masked by water retention. Serum insulin concentrations were doubled in obese animals but unchanged in lean phenotypes after GH treatment. Hepatic fatty acid oxidation in obese animals was stimulated 5-fold by treatment, while hepatic lipid synthesis was stimulated 2-fold and adipose lipid synthesis was reduced 3-fold. These results suggest that growth hormone induces a partitioning of nutrients in obese rats which results in less lipid accumulation.