Molecular Mechanism of Moderate Insulin Resistance in Adiponectin-Knockout Mice

Endocrine Journal

Kumpei TOKUYAMA¹  Kaoru SUGI⁵  Iseki TAKAMOTO³  Masao MOROI⁵  Tetsuya KUBOTA³  Takashi KADOWAKI³  Tetsuo NODA⁴  Shinsuke ITOH³  Hitomi OGATA¹  Wataru YANO³  Kohjiro UEKI³  Naoto KUBOTA³  Yasuo TERAUCHI²  Motoharu AWAZAWA³ 

[1] Graduate School of Comprehensive Human Sciences, University of Tsukuba;Department of Endocrinology and Metabolism, Yokohama City University Graduate School of Medicine;Department of Diabetes and Metabolic Disease, Graduate School of Medicine, University of Tokyo;Department of Cell Biology, Japanese Foundation for Cancer Research-Cancer Institute;Division of Cardiovascular Medicine, Toho University, Ohashi Hospital

关键词: Adiponectin;    Insulin resistance;    Adiponectin-knockout mice;    Euglycemic-hyperinsulinemic clamp;   

DOI  :  10.1507/endocrj.K08E-093

学科分类：内分泌与代谢学

来源: Japan Endocrine Society

【 摘 要 】

References(26)Cited-By(27)Adiponectin has been proposed to act as an antidiabetic adipokine, suppressing gluconeogenesis and stimulating fatty acid oxidation in the liver and skeletal muscle. Although adiponectin-knockout (adipo(-/-)) mice are known to exhibit insulin resistance, the degrees of insulin resistance and glucose intolerance are unexpectedly only moderate. In this study, the adipo(-/-) mice showed hepatic, but not muscle, insulin resistance. insulin-stimulated phosphorylation of IRS-1 and IRS-2 was impaired, the IRS-2 protein level was decreased, and insulin-stimulated phosphorylation of Akt was decreased in the liver of the adipo(-/-) mice. However, the triglyceride content in the liver was not increased in these mice, despite the decrease in the PPARalpha expression involved in lipid combustion, since the expressions of lipogenic genes such as SREBP-1 and SCD-1 were decreased in association with the increased leptin sensitivity. Consistent with this, the down-regulation SREBP-1 and SCD-1 observed in the adipo(-/-) mice was no longer observed, and the hepatic triglyceride content was significantly increased in the adiponectin leptin double-knockout (adipo(-/-)ob/ob) mice. On the other hand, the triglyceride content in the skeletal muscle was significantly decreased in the adipo(-/-) mice, probably due to up-regulated AMPK activity associated with the increased leptin sensitivity. In fact, these phenotypes in the skeletal muscle of these mice were no longer observed in the adipo(-/-)ob/ob mice. In conclusion, adipo(-/-) mice showed impaired insulin signaling in the liver to cause hepatic insulin resistance, however, no increase in the triglyceride content was observed in either the liver or the skeletal muscle, presumably on account of the increased leptin sensitivity.

【 授权许可】

Unknown