Lethal yellow mutation in the Raly-Agouti locus reduces the energy expenditure in male mice

The lethal yellow (A^Y) mutation in the Raly-Agouti locus leads to ectopic expression of the agouti protein in the brain where it inhibits melanocortin receptors, causes obesity as well as alters some traits of adaptive behavior. In the present study we used the Phenomaster calorimetric module tool to compare the travel distance, food and O₂ consumption as well as CO₂ excretion in 12 weeks old males of C57BL/6- A^Y and C57BL/6 mice. The A^Y mutation did not affect travelled distance and food consumption. At the same time, this mutation significantly reduced O₂ consumption and CO₂ excretion which are the main indices of indirect calorimetry. This result suggests that the reduced energy expenditure is a cause of obesity in C57BL/6- A^Y mice. These mutant mice seem to use energy received with food in a more economical way compared to C57BL/6 mice. The results of the present study increase the impact of C57BL/6- A^Y mice as a convenient model of neural and molecular mechanisms of economical expenditure of energy resources.