Differential early rearing affects response to overfeeding in B6D2F2 mice

Area of Science:

• Animal Physiology
• Nutritional Science
• Developmental Biology

Background:

• Early life experiences, such as litter size, can influence long-term physiological adaptations.
• Dietary interventions in adulthood can impact body weight and metabolic parameters.

Purpose of the Study:

• To investigate the combined effects of early rearing litter size and adult diet on body weight regulation and thermogenic capacity in mice.
• To determine if early life environment influences metabolic responses to diet and cold exposure.

Main Methods:

• Male and female mice were reared in small, medium, or large litters.
• Mice were fed either a high-fat, high-carbohydrate (EXP) or a chow (CH) diet from 14 weeks of age.
• Thermogenic capacity was assessed via oxygen consumption and body temperature during cold stress, with analysis of interscapular brown adipose tissue (1BAT).

Main Results:

• Mice on the EXP diet consumed more calories and gained more weight than CH mice, with the greatest effect in small-litter (Sm) mice.
• Caloric efficiency was highest in Sm EXP mice and males.
• Body fat increased with smaller litter size and the EXP diet in males.
• Sm mice showed less temperature decrease and lower oxygen consumption per gram body weight during cold stress, suggesting increased insulation.
• Neither litter size nor diet affected 1BAT protein content or cytochrome c oxidase activity.

Conclusions:

• Early rearing experience, specifically litter size, influences behavioral and physiological variables related to adult body weight maintenance.
• These effects appear to be independent of changes in brown adipose tissue thermogenic function.