Differential early rearing affects response to overfeeding in B6D2F2 mice.
Male and female B6D2F2 mice, reared in small (Sm = 4), medium (Md = 8) and large (Lg = 12) litters, were maintained on high-fat, high-carbohydrate (EXP) or chow (CH) diets beginning at 14 weeks. EXP mice consumed more calories and gained more weight than CH mice; these effects were greatest in the Sm animals. Each sex responded similarly. Caloric efficiency was highest in the Sm EXP and male animals. Total body fat in males showed that Sm greater than Md greater than Lg and EXP greater than CH. The thermogenic capacity was measured by total oxygen consumption and body temperature response during acute cold stress, and protein content and cytochrome c oxidase activity in interscapular brown adipose tissue (1BAT). Sm mice had a smaller decrease in temperature and consumed less oxygen per gram body weight than Lg, suggestive of a contributing role of increased insulation. When oxygen consumption was expressed as a function of body weight0.75, EXP greater than CH, but there were no other significant dietary effects. Neither litter size nor diet appeared to affect protein content or cytochrome c oxidase activity in 1BAT. These results show that early rearing experience effects both behavioural and physiological variables associated with the maintenance of adult body weight in mice, but these effects do not appear to be mediated through 1BAT.
Department of Health Studies, University of Waterloo, Ontario, Canada.
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P
Wainwright
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Hoffman-Goetz
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C
Young
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D
Gardner
D000818:Animals; D001833:Body Temperature Regulation; D001835:Body Weight; D004040:Dietary Carbohydrates / Q000008:administration & dosage; D004041:Dietary Fats / Q000008:administration & dosage; D005247:Feeding Behavior / Q000502:physiology*; D005260:Female; D008098:Litter Size; D008297:Male; D051379:Mice; D010101:Oxygen Consumption
D004040:Dietary Carbohydrates; D004041:Dietary Fats