Abstract
BACKGROUND/OBJECTIVE: Eicosapentaenoic acid (EPA) exerts pleiotropic effects on metabolic disorders such as atherosclerosis and dyslipidemia, but its effectiveness in the treatment of type 2 diabetes mellitus remains controversial. METHODS: We examined the antidiabetic effect of EPA in insulin receptor mutant (Insr(P1195L/+)) mice that exhibit high-fat diet (HFD)-dependent hyperglycemia. RESULTS: EPA supplementation was found to alleviate hyperglycemia of Insr(P1195L/+) mice fed HFD (Insr(P1195L/+)/HFD mice), which was accompanied by amelioration of increased gluconeogenesis and impaired insulin signaling, as assessed by glucose-6-phosphatase (G6pc) expression on refeeding and insulin-induced phosphorylation of Akt in the liver, respectively. We found that serum levels of adiponectin, the antidiabetic adipokine, were decreased by HFD along with the body weight gain in Insr(P1195L/+) mice but not in wild-type mice, suggesting that Insr(P1195L/+) mice are prone to hypoadiponectinemia in response to obesity. Interestingly, the blood glucose levels of Insr(P1195L/+) mice were in reverse proportion to their serum adiponectin levels and EPA supplementation ameliorated their hyperglycemia in conjunction with the restoration of hypoadiponectinemia. CONCLUSIONS: EPA exerts an antidiabetic effect in Insr(P1195L/+)/HFD mice, an HFD-sensitive, insulin-resistant animal model, possibly through its action against hypoadiponectinemia.