Quercetin is a food component that may ameliorate the diabetic symptoms. We examined hepatic gene expression of BALB/c mice with streptozotocin (STZ)-induced diabetes to elucidate the mechanism of the protective effect of dietary quercetin on diabetes-associated liver injury. We fed STZ-induced diabetic mice with diets containing 0.1% or 0.5% quercetin for 2 weeks and compared the patterns of hepatic gene expression in these groups of mice using a DNA microarray. Diets containing 0.1% or 0.5% quercetin lowered the STZ-induced increase in blood glucose levels and improved plasma insulin levels. A cluster analysis of the hepatic gene expressions showed that 0.5% quercetin diet suppressed STZ-induced alteration of gene expression. Gene set enrichment analysis (GSEA) and quantitative RT-PCR analysis showed that the quercetin diets had their greatest suppressive effect on the STZ-induced elevation of expression of cyclin dependent kinase inhibitor p21(WAF1/Cip1) (Cdkn1a).
Overall design
Six-week-old male mice were divided into 4 groups of 6 mice each, housed in groups of 3 per cage. After 1 week mice were intraperitoneally injected with STZ. Mice (n=6) in the untreated control group did not receive any treatment. After 1 week, 18 mice showing non-fasting blood glucose levels of 230-400 mg/dL were divided into 3 groups: one group was fed with AIN93G only (control group), the others with an AIN93G diet containing 0.1% or 0.5% quercetin (Funakoshi, Tokyo, Japan) for 2 weeks.
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