Western Diet Induces Changes in Gene Expression in Multiple Tissues During Early Insulin Resistance and Glucose Intolerance in Male C57BL/6 Mice.

To better understand the molecular mechanisms by which a Western diet (WD) promotes the development of type 2 diabetes (T2D), we analyzed changes in the expression profiles of multiple glucose-regulatory tissues of male C57BL/6 mice. We fed the mice with either a regular control diet (CD) or a WD. Standard glucose and insulin tolerance tests were performed, and body weight, plasma glucose, and triglyceride levels were measured to assess the glucose homeostasis in vivo. The WD induced obesity, glucose intolerance, and insulin resistance, with a fasting hyperglycemia. Further, we identified several changes in the gene expression of the analyzed candidate genes in all the examined target tissues, including the downregulation of Tcf7l2 in the liver, pancreas, white and brown adipose tissue (0.72, 0.56, 0.36, and 0.22-fold, respectively), in contrast to a marked upregulation in the intestine (2.57-fold). We also found downregulation of PPARγ in the white and brown adipose tissue (0.55, 0.41-fold, respectively) and upregulation in the pancreas, liver, intestine, and skeletal muscle (1.25, 1.46, 1.97, and 2.59-fold, respectively). Our findings provide important insight into the characteristic pattern of changes in expression of candidate genes during the early stages of insulin resistance and glucose intolerance in this diet-induced mouse model of T2D.