SOYBEAN PROTEIN SUPPRESSES HEPATIC LIPOGENIC ENZYME GENE-EXPRESSION IN WISTAR FATTY RATS

The effects of dietary soybean protein on lipogenic enzyme gene expres sion in livers of genetically fatty rats (Wistar fatty) have been inve stigated. When Wistar fatty rats and their lean littermates (7-8-wk ol d) were fed a casein or soybean protein isolate diet containing hydrog enated fat (4% hydrogenated fat plus 1% corn oil) or corn oil (5%) for 3 wk, the hepatic messenger RNA concentrations and activities of lipo genic enzymes were significantly lower in rats fed soybean protein tha n in those fed casein, regardless of genotype or dietary fat. The conv ersion rates of thyroxine to triiodothyronine by liver microsomes and plasma triiodothyronine concentrations were lower in the fatty rats th an in the lean rats and were significantly greater in rats fed soybean protein than in those fed casein. Conversely, plasma and liver triacy lglycerol concentrations were lower in soybean protein-fed fatty and l ean rats than in those fed casein. The body weight was less in the fat ty rats fed soybean protein than in those fed casein after 3 wk of fee ding. Moreover, dietary polyunsaturated fatty acids suppressed lipogen ic enzyme gene expression in the lean rats but did not in the fatty ra ts. Dietary soybean protein appeared to be useful for the reduction of obesity.