Effect of high-fat diet on gene expression of GLUT4 and insulin receptor in soleus muscle.

Gene expression of GLUT4 and insulin receptor in soleus muscle of high-fat and high-carbohydrate diet fed rats was studied by measuring mRNA. High-fat diet feeding increased plasma glucose but decreased plasma insulin level. Glucose uptake in soleus muscle measured by 2-deoxy-D-glucose technique was lower in high-fat than high-carbohydrate diet fed rats. GLUT4 mRNA level in soleus muscle was significantly decreased but insulin receptor mRNA was similar in high-fat compared with high-carbohydrate diet fed rats. Insulin receptor exists in two forms generated by alternative splicing of a primary gene transcript. There was no difference in the relative expression of insulin receptor isoform mRNAs between high-fat and high-carbohydrate diet fed rats. These results suggest that high-fat diet impairs glucose metabolism in muscle by reducing transcription of GLUT4 without affecting gene expression of insulin receptor.