JTT-501, a novel oral antidiabetic agent, improves insulin resistance in genetic and non-genetic insulin-resistant models

1. We investigated whether JTT-501 (4-[4-[2-(5-methyl-2-phenyl-4-oxazolyl)ethoxy]benzyl]-3,5-isoxazolidinedione) would improve insulin resistance in genetic (Zucker fatty rats) and non-genetic (high-fat fed rats) rodent models of obesity. 2. JTT-501 (10–100 mg kg(−1) day(−1)) was administered orally to Zucker fatty rats for 7–21 days. In the high-fat fed rat model, JTT-501 (100 mg kg(−1) day(−1)) was administered orally for 7 days. In both models, JTT-501 improved metabolic abnormalities by enhancing insulin action during the glucose tolerance test and the euglycaemic-hyperinsulinaemic clamp study. In ex vivo assays, JTT-501 ameliorated the impaired insulin-sensitive glucose oxidation and lipid synthesis in peripheral tissues. Furthermore, JTT-501 enhanced insulin receptor autophosphorylation in hindlimb muscle. 3. JTT-501 reduced serum leptin concentrations in both models, but did not affect body weight or epididymal fat weight. 4. Our observations indicate that JTT-501 improves the metabolic abnormalities in both genetic and non-genetic insulin-resistant models by enhancing insulin action in peripheral tissues. These effects of JTT-501 are due, at least in part, to enhanced insulin receptor autophosphorylation. In addition, JTT-501 is able to reduce serum leptin concentrations in hyperleptinaemia of the insulin-resistant model. We expect JTT-501 to show promise for treating non-insulin dependent diabetes mellitus patients with insulin resistance

Effects of peroxisome proliferator-activated receptor-α and -γ agonist, JTT-501, on diabetic complications in Zucker diabetic fatty rats

1. This study has investigated the effects of JTT-501, a peroxisome proliferator-activated receptor (PPAR)-α and PPAR-γ agonist, on the pathogenesis of diabetic complications in the Zucker diabetic fatty (ZDF) rats, a model of type 2 diabetes. Comparison is made with troglitazone, a PPAR-γ agonist. 2. The ZDF rats exhibited hyperglycaemia and hyperlipidaemia, and developed diabetic complications such as cataract, nephropathy, and neuropathy. Treatment with JTT-501 from the prediabetic stage controlled glycaemia and lipidaemia, and prevented the development of diabetic complications. Troglitazone was less effective in controlling serum cholesterol and neuropathy. 3. ZDF rats developed diabetic osteopenia with reduced bone turnover, and this was prevented by JTT-501 and troglitazone, possibly mediated by increased bone turnover and bone formation. 4. Since JTT-501 controlled glycaemia and lipidaemia in ZDF rats and prevented several diabetic complications, it is suggested that treatment with JTT-501, which activates both PPAR-α and PPAR-γ, could provide a valuable therapeutic approach against diabetic complications in type 2 diabetes