Metabolism of Glucose and Acetate in Obese Rats

Abstract

To determine the mechanism leading to obesity when Osborne-Mendel rats are fed a high fat diet, the effect of dietary fat level on glucose and acetate metabolism was studied. Metabolism was followed at 3- or 6-week intervals by measurement of 14C in expired carbon dioxide after intraperitoneal administration of 2 µc of glucose-1-14C, glucose-6-14C, or sodium acetate-1-14C. Differences between the groups fed at the 2 levels of fat were observed, but showed no trends which might explain the obesity of rats fed the high fat diet, although at 15 and 21 weeks after weaning this group excreted less of the dose of acetate-1-14C than did rats fed the 5% fat diet. The percentage of dose of glucose-1-14C expired as CO2 decreased sharply between 1 and 6 weeks in both diet groups. This decrease was also noted after administration of glucose-6-14C to rats fed the 60% fat diet, and the decrease continued until 21 weeks. The percentage of dose expired after administration of sodium acetate-1-14C did not change with increasing age in either diet group. However, the rats fed the 60% fat diet excreted carbon dioxide of lower specific activity than those fed the 5% fat diet at 9, 15, and 21 weeks after weaning.