Acetone metabolism in mice: increased activity in mice heterozygous for obesity genes.

Mice were found to convert acetone to lactate at appreciable rates. The conversion of acetone to gluconeogenic precursors could provide additional glycolytic intermediates that would allow the more complete utilization of lipid stores and increase survival time during starvation. In mice that were starved for 3 days or were provided with acetone in the drinking water the acetone-metabolizing pathway was induced to levels severalfold normal. Mice heterozygous for obesity-producing mutations, either obese (ob/+) or diabetes (db/+), showed induction of the activity of this pathway to a significantly higher degree than did homozygous normal (+/+) mice of the same strain. This more effective conversion of acetone to lactate exhibited by heterozygous mice could account for their prolonged survival on a starvation regimen compared to that of normal homozygotes. The rate-limiting step in the pathway appears to be the conversion of acetone to a hydroxylated derivative. The enzyme system effecting this conversion is an NADPH-requiring microsomal oxygenase found in the liver.