Increased lipid accumulation in liver and white adipose tissue in aging in the SAMP10 mouse.

The population of elderly persons has increased worldwide. However, few studies have examined age-dependent changes in lipid and carbohydrate metabolism related to age-related diseases. The number of cases of metabolic syndrome is increasing worldwide and prevention of lifestyle diseases may lead to prolongation of lifespan. In this study, we examined age-dependent changes in lipid and carbohydrate metabolism in the senescence-accelerated (SAM) P10 mouse. Tissue weights and biochemical parameters in plasma and liver were examined in SAMP10 mice aged 3, 6, 9, and 12 mo. White adipose tissue weight and the levels of liver triacylglycerol, plasma free fatty acids, and plasma insulin all showed increases with aging of the mice. To examine this mechanism in detail, aging-related changes in mRNA expression of genes related to lipid and carbohydrate metabolism were examined by DNA microarray analysis. The mRNA level for Hsd11b1 (hydroxysteroid 11-beta dehydrogenase 1), which increases insulin secretion and resistance, was elevated with aging in the liver of SAMP10 mice. These results show that lipid accumulation in liver and white adipose tissue is promoted by aging in SAMP10 mice through an increase in plasma insulin levels.