Gene expression profiling of adipose tissues in obesity susceptible and resistant rats under a high fat diet

Different responses to a high fat diet (HFD) can occur even within a group of animals with the same genetic background, such as obesity-prone (OP) or obesity-resistant (OR) phenotypes, on the same feeding. To explain these phenotypes, we performed an analysis of gene expression differences in brown (BAT) and white adipose tissue (WAT) of OP and OR rats. Microarray analysis of transcripts revealed that 91 and 53 genes showed significant differences in expression between the BAT and WAT gene, respectively. Surprisingly, a majority of these genes were significantly down-regulated in adipose tissues in response to HFD feeding. K-means clustering of the expression levels of these genes identified 4 distinct groupings of genes with significant expression levels. Only a limited number of genes were significantly regulated in adipose tissues in response to HFD feeding, whereas expression levels of a large number of genes differed significantly between OP and OR rat. Our observations support that distinct discrepancies exist in gene-expression regulations in adipose tissues, and that alteration likely resulted from significant differences in genes encoding metabolic enzymes. To the best of our knowledge, this study provided the first direct comparison of gene-expression changes between OP and OR rats.