We investigated lipid and lipoprotein abnormalities in SHRSP fatty rats as a new animal model of metabolic syndrome. We examined differentially expressed genes in the liver, one of the major tissues contributing to lipid metabolism. Using gel filtration high performance liquid chromatography, increased cholesterol concentrations of small particle size low-density lipoprotein (LDL) fractions were observed in SHRSP fatty rats, whereas the Zucker Fatty strain did not show a similar elevation of cholesterol content. Existence of apolipoprotein B in these fractions was confirmed by Western blotting. The small particle size of the LDL fractions was significantly decreased by a 4-week fenofibrate treatment. Microarray analysis identified seventeen genes that were significantly upregulated and ten that were significantly decreased in liver tissues of SHRSP fatty rats compared with levels in SHRSP rats. Stearoyl-coenzyme A desaturase 1, fatty acid synthase, ATP citrate lyase, and sterol regulatory element binding factor 1 genes were among the upregulated genes. These findings suggest that SHRSP fatty rats carry small dense LDL like particles which is a common lipid abnormality in the metabolic syndrome. Three of ten genes upregulated in liver tissues of SHRSP fatty rats play a role in this metabolic abnormality and are a therapeutic target of this metabolic syndrome.

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