Role of Supplementary Selenium on the Induction of Insulin Resistance and Oxidative Stress in NSY Mice Fed a High Fat Diet

The role of supplementary selenium on the induction of insulin resistance and oxidative stress in a diabetic mouse model was investigated in NSY mice on a high fat diet (HFD) and administered seleno-L-methionine (SeMet)-containing water for 12 weeks. Significant increases in oral glucose tolerance-tested (OGTT), insulin tolerance-tested, and non-fasting blood glucose levels were observed in mice on a HFD, as well as the significant increases in OGTT and non-fasting plasma insulin levels. Mice on a HFD had decreased plasma adiponectin levels and increased free fatty acid (FFA) levels. Supplementary SeMet significantly augmented OGTT blood glucose levels in mice on a HFD and plasma FFA levels in mice on a normal diet. The mRNA levels of six selenoproteins were measured, and glutathione peroxidase (GPx) 1 and selenoprotein P (SelP) were selected as candidates that may be associated with insulin resistance or oxidative stress in the liver. Hepatic GPx1 expression was elevated in mice on a HFD and SeMet supplementation, and SelP expression increased in mice on a HFD. Histopathological observations in hepatic tissues showed hypertrophy of parenchymal cells and significant expression of 4-hydroxy-2-nonenal in mice on a HFD, indicating lipid accumulation and oxidative stress induction. Hepatic protein tyrosine phosphatase activity also increased by a HFD. These results suggest that hepatic lipid accumulation in NSY mice on a HFD promoted oxidative stress and hepatic SelP expression, and supplementary SeMet induced hepatic GPx1 expression.