DIET FAT ALTERS EXPRESSION OF GENES FOR ENZYMES OF LIPOGENESIS IN LEAN AND OBESE MICE

The objective of this experiment was to determine the effect of polyun saturated fatty acids on gene expression for fatty acid synthase, acet yl CoA-carboxylase, malic enzyme, pyruvate kinase, and phosphoenolpyru vate carboxykinase in obese mice. Eight-week-old female lean and obese mice were fed semi-purified diets containing 20% (w/w) fat of either high or low polyunsaturated to saturated (P/S) fatty acid ratio for fo ur weeks. Total RNA was isolated from liver and was hybridized to cDNA probes for the above enzymes. Consumption of a high P/S diet decrease d mRNA levels for all the lipogenic enzymes studied in both lean and o bese mice. Compared to lean mice, obese mice exhibited a higher mRNA l evel for fatty acid synthase, acetyl CoA-carboxylase, malic enzyme, an d pyruvate kinase in animals fed either a high or low P/S diet. Enzyme -specific activities followed the same profile as the mRNA levels in b oth lean and obese mice fed a high or low P/S diet. The decrease in li ver fatty acid synthase mRNA level was more pronounced in lean mice co mpared to obese mice, suggesting that the obese mice may be more resis tant to polyunsaturated fatty acid feedback control of gene expression .