The role of SOCS2 in recombinant human growth hormone (rhGH) regulating lipid metabolism in high-fat-diet-induced obesity mice

Abstract

In addition to regulate body growth and development process, growth hormone (GH) also involved in lipid metabolism, decreasing fat mass and improving lipolysis. To normal mice, GH could reduce their fat content, but events turned uncertain coming to the pattern of feeding high-fat-diet. In order to investigate the role of GH in adipogenesis of mice with high-fat-diet, the high-fat-diet feeding mice were randomly assigned into three groups and treated with recombinant human growth hormone (rhGH) and the somatostatin analogue octreotide respectively. Results demonstrated that both rhGH and octreotide could reduce the body weight but the trends diminished in the end. HDL-C level was increased in octreotide treated groups but the activity of lipase was increased significantly in both two groups. RhGH remarkable increased the expression of SOCS2, FAS (P < 0.01) and SREBP-1c (P < 0.05), decreased the expression of SOCS1, SOCS3 (P < 0.05) and HSL (P < 0.01) in subcutaneous fat mass. In visceral fat tissue, all genes were increased except SOCS2 (P < 0.01), at the same time the visceral fat mass was decreased. The protein phosphorylation of JAK2 and STAT5 which were treated with octreotide were increased in subcutaneous fat, visceral fat and liver (P < 0.01) and were increased significant in visceral fat by rhGH treated (P < 0.01). In liver, only JAK2 protein phosphorylation was raised (P < 0.01). In conclusion, rhGH and octreotide could decrease the whole body mass before 6 days; the trend was weaken in later period with high-fat-diet. RhGH could increase the subcutaneous fat mass and reduce the visceral fat mass, and SOCS2 might be involved in regulation of the mechanism through JAK2/STAT5 signaling pathway.