Profound differences in fat versus carbohydrate preferences in CAST/EiJ and C57BL/6J mice: Role of fat taste

In a nutrient self-selection study, CAST/EiJ mice consumed more carbohydrate than fat while C57BL/6J (B6) mice showed the opposite preference. The present study revealed similar strain differences in preferences for isocaloric fat (Intralipid) and carbohydrate (sucrose, maltodextrin) solutions in chow-fed mice. In initial 2-day choice tests, percent fat intakes of CAST and B6 mice were 4-9% and 71-81% respectively. In subsequent nutrient vs. water tests, CAST mice consumed considerably less fat but not carbohydrate compared to B6 mice. Orosensory rather than postoral factors are implicated in the very low fat preference and intake of CAST mice. This is supported by results of a choice test with Intralipid mixed with non-nutritive sweeteners vs. non-sweet maltodextrin. The preference of CAST mice for sweetened fat exceeded that of B6 mice (94 vs. 74%) and absolute fat intakes were similar in the two strains. When given unsweetened Intralipid vs. water tests at ascending fat concentrations CAST mice displayed reduced fat preferences at 0.1-5% and reduced intakes at 0.5-5% concentrations, compared to B6 mice. The differential fat preferences of CAST and B6 mice may reflect differences in fat taste sensing or in central neural processes related to fat selection.