Effect of dietary fats differing in degree of unsaturation on gene expression in rat adipose tissue.

To test the possibility that the type of dietary fat affects the expression of proteins involved in adipose tissue metabolism, levels of mRNA for lipoprotein lipase, leptin, glucose transporter 4, and uncoupling protein in adipose tissues were compared among rats fed a low-fat diet (2% safflower oil), and high-fat diets containing 20% saturated fat (palm oil) or unsaturated fat rich in linoleic acid (safflower oil) for 3 weeks. High-fat diets decreased the lipoprotein lipase mRNA level in epididymal but not in perirenal white adipose tissue, but increased it in brown adipose tissue. Leptin gene expression in perirenal white adipose tissue was significantly higher in rats fed high-fat diets than in those fed a low-fat diet. High-fat diets failed, however, to alter this parameter in epididymal white adipose tissue and interscapular brown adipose tissue. mRNA levels of glucose transporter 4, both in epididymal and perirenal white adipose tissues, were lower in rats fed high-fat diets than in those fed a low-fat diet. Uncoupling protein gene expression in interscapular brown adipose tissue was 2-3 times higher in rats fed high-fat diets than in those fed a low-fat diet. The abundance of mRNAs for lipoprotein lipase, leptin, glucose transporter 4 and uncoupling protein was, however, comparable between rats fed diets high in safflower and palm oil. We concluded that the high-fat diet influences gene expression of adipose tissue in a site-specific manner. The difference in the degree of unsaturation of dietary fats is rather irrelevant in modifying the level of mRNAs for proteins related to energy metabolism and expenditure in adipose tissue.