Effect of voluntary exercise on genetically obese Cpe^fat/fat mice: Quantitative proteomics of serum

Objective: To compare the effect of voluntary exercise on body weight, food consumption, and levels of serum proteins between wild-type and carboxypeptidase E-deficient (Cpe^fat/fat) mice. Research Methods and Procedures: Study 1 consisted of three groups of female mice: Cpe ^fat/fat mice with continuous access to exercise wheels for 3 weeks (n = 4); wild-type C57BKS mice with access to exercise wheels for 3 weeks (n = 4); and sedentary Cpe^fat/fat mice (n = 3). Activity, body weight, and food consumption were monitored for this period and a subsequent 9-week period without exercise wheels. Study 2 consisted of four groups of male mice (n = 6 to 7 each): Cpe^fat/fat mice with exercise wheels, wild-type mice with exercise wheels, and Cpe^fat/fat and wild-type mice without exercise wheels. Body weight and food consumption were measured over 4 weeks. Sera were collected, and the protein profile was determined by 2-dimensional gel electrophoresis and mass spectrometry. Results: Cpe^fat/fat mice were moderately hyperphagic but lost weight during the initial exercise period because of greater energy expenditure. The effect of exercise was temporary, and the mice gained weight after the second week. Several serum proteins were found to be altered by exercise: haptoglobin was decreased by exercise in Cpe ^fat/fat mice, and several kallikreins were increased by exercise in wild-type mice. Discussion: The access to exercise wheels provided an initial weight loss in Cpe^fat/fat mice, but this effect was offset by elevated food consumption. The serum proteomics results indicated that Cpe ^fat/fat and wild-type mice differed in their response to exercise.