Macronutrient diet selection in thirteen mouse strains

The strain distribution for macronutrient diet selection was described in 1 3 mouse strains (AKR/J, NZB/B1NJ, C57BL/6J, C57BL/6ByJ, DBA/2J, SPRET/Ei, C D-1, SJL/J, SWR/J, 129/5, BALB/cByJ, CAST/Ei, and A/J) with the use of a se lf-selection protocol in which separate carbohydrate, fat, and protein diet s were simultaneously available for 26-30 days. Relative to carbohydrate, n ine strains consumed significantly more calories from the fat diet; two str ains consumed more calories from carbohydrate than from fat (BALB/cByJ, CAS T/Ei). Diet selection by SWR/J mice was variable over time, resulting in a lack of preference. One strain (A/J) failed to adapt to the diet paradigm d ue to inadequate protein intake. Comparisons of proportional fat intake acr oss strains revealed that fat selection/consumption ranged from 26 to 83% o f total energy. AKR/J, NZB/B1NJ, and C67BL/6J mice self-selected the highes t proportion of dietary fat, whereas the CAST/Ei and BALB/cByJ strains chos e the lowest. Finally, epididymal fat depot weight was correlated with fat consumption. There were significant positive correlations in AKR/J and C57B L/6J mice, which are highly sensitive to dietary obesity. However, absolute fat intake was inversely correlated with epididymal fat in two of the lean strains: SWR/J and CAST/Ei. We hypothesize that the SWR/J and CAST/Ei stra ins are highly sensitive to a negative feedback signal generated by increas ing body fat, but the AKR/J and C67BL/6J mice are not. The variation in die tary fat selection across inbred strains provides a tool for dissecting the complex genetics of this trait.