X. Endogenous dilution of administered labeled acetate during lipogenesis and cholesterogenesis in two types of obese mice

Abstract

Determination of dilution of administered labeled acetate by endogenously produced acetate in two types of obese mice: goldthioglucose obese mice (regulatory obesity) and obese hyperglycemic mice (metabolic obesity) shows that this dilution is of the same order for obese and non-obese mice when fed ‘ad libitum.’ When fasted, dilution is again of the same order for goldthioglucose obese mice and normal controls, but is twice as great for obese hyperglycemic mice. These data in conjunction with results obtained on incorporation of C¹⁴ into fatty acids and cholesterol show that the increased synthesis of these lipids is related solely to the hyperphagia in the case of the goldthioglucose obese mice. By contrast, the obese-hyperglycemic mice show rates of fatty acid and cholesterol synthesis which are three times the control levels even when fasted. These results justify the previously drawn distinction between ‘regulatory’ and ‘metabolic’ obesities.