LIPID-LEVEL AND TYPE ALTER STEAROYL-COA DESATURASE MESSENGER-RNA ABUNDANCE DIFFERENTLY IN MICE WITH DISTINCT SUSCEPTIBILITIES TO DIET-INFLUENCED DISEASES

Chronic diseases develop in susceptible individuals following exposure to environmental conditions including high fat diets. Inbred strains of mice differing in susceptibility to atherosclerosis, diabetes, obes ity and certain cancers are models for understanding the genetic basis and molecular mechanisms whereby diet influences these polygenic and multifactorial disorders. Expression sequence tags (EST) and disease q uantitative trait loci (QTL) are also being identified with these stra ins. Reported here are comparisons of food intake, growth, nonfasting serum lipids and expression of mRNA for hepatic apolipoprotein E (ApoE ), hepatic stearoyl CoA desaturase (Scd1) and heart lipoprotein lipase (Lpl) in a 2 x 2 x 2 design with C57BL/6J and BALB/cByJ mice fed semi purified diets with 4 or 20% saturated (coconut) or unsaturated (corn) oils for 4 mo. Histological studies of aortas and coronary arteries a re also reported for these animals. After 4 mo, BALB/cByJ mice were si gnificantly heavier and had significantly higher total serum cholester ol, HDL cholesterol and triglyceride concentrations in the fed state t han C57BL/6J mice. Efficiency of utilizing dietary energy did not diff er consistently between strains. Oil level affected serum total choles terol, triglycerides and HDL cholesterol, which were significantly gre ater in mice fed high fat diets. Lpl and ApoE mRNA expression levels w ere not significantly affected by mouse strain, oil source or oil leve l. Scd1 mRNA expression, however, was significantly higher in C57BL/6J than in BALB/cByJ mice and was lower in all mice fed 20% compared wit h those fed 4% fat diets. Genes regulated differently by diet among st rains with distinct susceptibility to diet-influenced disease may be a ssociated with molecular pathways contributing to incidence or severit y.