Adipose tissue metabolism of obese mice on standard and high-fat diets

¹ Departments of Medicine, Harvard Medical School and Peter Bent Brigham Hospital; Baker Clinic Research Laboratories, New England Deaconess Hospital; and Department of Nutrition, Harvard School of Public Health, Boston, Massachusetts

Adipose tissue metabolism in vitro was studied, after substitution for several weeks of synthetic low-carbohydrate, high-fat (saturated or unsaturated) diets for the standard chow diet, in obese hyperglycemic mice and in their nonobese littermates. In tissue from nonobese mice fed the high-fat diets, glucose metabolism to CO₂ and to fatty acids was diminished in the absence of added hormone, while glucose carbon incorporation to glyceride-glycerol was increased. Under insulin (0.1 unit/ml) stimulation, total glucose uptake was relatively decreased by the diets, as was glucose metabolism to CO₂, to fatty acids, and to glycogen; however, glucose carbon incorporation to glyceride-glycerol was unaltered. Under epinephrine stimulation, the sum of glucose carbon recovery was less after high-fat feeding. No effect of high-fat feeding was detected on base-line rates of free fatty acid release nor on the effects of insulin or epinephrine on this process. No differences were found between the effects of saturated- or unsaturated-fat diets on any parameters. The metabolism of adipose tissue from obese mice was slightly, if at all, affected by high-fat feeding. These results are discussed in reference to the normal adaptation to low-carbohydrate, high-fat diets and to the metabolic abnormalities present in obese hyperglycemic mice.