Gene in mice controls food cravings, desire to exercise

Prkar2a contains the information needed to make two subunits -- molecular components -- of the enzyme protein kinase A. Enzymes speed up chemical reactions, either helping to combine smaller molecules into larger molecules, or to break down larger molecules into smaller ones. Protein kinase A is the central enzyme that speeds reactions inside cells in many species. In a previous study, the NICHD team found that despite being fed a high fat diet, mice lacking functioning copies of Prkar2a were less likely to become obese than wild type mice with normally functioning Prkar2a.

The researchers determined that Prkar2a-negative mice ate less high-fat food than their counterparts, not only when given unlimited access to the food, but also after a fast. Similarly, the Prkar2a negative mice also drank less of a sugar solution than the wild type mice. The Prkar2a-negative mice were also more inclined to exercise, running 2-3 times longer than wild type mice on a treadmill. Female Prkar2a-negative mice were less inclined to consume high fat foods than Prkar2-negative males, while Prkar2-negative males showed less preference for the sugar solution than Prkar2-negative females.