The effect of varying dietary macronutrient content on the body composition of AKR/J and SWR/J mice was examined. Dietary fat was fed at three levels (45, 30, and 15 kcal%), while dietary protein also was varied across three levels (10, 20, and 30 kcal%). All mice were placed on the defined diets at 5 wk of age and maintained on these diets for 12 wk. AKR/J mice were significantly larger and had a significantly greater carcass fat content compared with SWR/J mice in all dietary conditions. There was a clear dose-response effect of dietary fat on body fat in the AKR/J mice. In contrast, SWR/J mice showed an increase of body fat only when fed the diet containing the highest level of dietary fat and the lowest protein concentration. High levels of dietary protein (30 kcal%) resulted in a significant decrease of carcass fat in the AKR/J mice compared with diets containing either 20 or 10 kcal% protein. This effect of protein was not observed in the SWR/J mice except in the groups fed the 45 kcal% fat diets. These findings demonstrate a strong interaction of genetic background and macronutrient content of the diet on body composition. The AKR/J strain of mouse has a greater percentage of carcass fat and is more responsive to the effects of dietary fat composition compared with the SWR/J strain.
We describe a new multiple gene mouse model of differential sensitivity to dietary obesity that provides a tool for dissecting the genetic basis for body composition and obesity. AKR/J and SWR/J male mice, as well as male progeny of intercrosses between these strains, were fed a high-fat diet for 12 weeks beginning at 5 weeks of age. Body weight and energy intake were assessed weekly. At the conclusion of the dietary manipulation, an adiposity index was calculated by dividing the weight of seven dissected adipose depots by the carcass weight. AKR/J mice had approximately sixfold greater adiposity than SWR/J mice. Examination of the segregation of the adiposity trait in the progeny of crosses between these strains indicates that the trait is determined by a minimum of one to four genetic loci and that there is significant dominance of the AKR/J genotype. A preliminary analysis with markers linked to the known mouse obesity genes ob, db, tub, and fat showed no linkage with these loci. However, a quantitative trait locus was found that maps distal to the db gene on Chromosome (Chr) 4. This locus has been designated dietary obese 1 or Do1.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.