Metabolic adaptations of three inbred strains of mice (C57BL/6, DBA/2, and 129T2) in response to a high-fat diet.

Although it is now becoming more evident that the strain of mouse used to generate genetically modified models for the study of endocrine disorders contributes to the ensuing phenotype, metabolic charac- terization of these common strains used to produce genetically altered mice has been limited. The aim of this study therefore was to measure various metabolic parameters in C57BL/6, DBA/2, and 129T2 mice fed a control or a high-fat diet. Mice were fed either a control (7 g/100 g) or a high-fat (60 g/100 g) diet for 6 wk. During wk 6, spontaneous and voluntary physical activity and resting energy expenditure were determined. DBA/2 mice that consumed the control diet gained more weight and had larger regional fat pad depots than either C57BL/6 or 129T2 mice (P 0.05). Spontaneous and voluntary activity was lower in 129T2 mice compared with DBA/2 or C57BL/6 mice (P 0.05). Resting energy expenditure (corrected for body weight) was greater in C57BL/6 mice than in DBA/2 or 129T2 mice (P 0.05), whereas glucose and fat oxidation did not differ among the 3 strains of mice. Plasma glucose concentrations in food-deprived mice were higher and insulin concentrations lower in 129T2 compared with C57BL/6 mice (P 0.05), but were not affected by the high-fat diet in any of the 3 strains tested. This study shows that these 3 commonly used inbred strains of mice have different inherent metabolic charac- teristics. It further highlights that the background strain used to produce genetically modified mice is critical to the resultant phenotype. J. Nutr. 134: 3264-3269, 2004.