Relationship between muscle mass and physical activity, behavior and cognitive function

The research problem: The relationship between body mass or composition and cognitive function, activity, and behavior has not been extensively presented in either Lithuanian or foreign scientific resources. The aim: To determine the differences in physical activity, behavior, and cognitive function between high and low muscle mass mice. Object of the study: The relationship between body and muscle mass with physical activity, behavior, and cognitive function. Research tasks: 1. To determine the differences of behavior in the new environment between mouse strains of different body size. 2. Identify the learning of the Lashley III maze and compare it between mouse strains of different body size. 3. To videorecord and compare daily spontaneous activity of different mouse strains in the cage. 4. To measure daily spontaneous activity of mice of different strains in the running wheel. Hypotheses: 1. Mice with higher body and muscle mass also show higher activity under various conditions. 2. Mice with higher body and muscle mass also have better cognitive function. Research methods and main results: Four strains of long-term selection for contrasting body size mice male were used in the study: Dummerstorf strain with high lean mass (DUH) weighing 91.0 ± 6.2 g; Berlin low strain with functional myostatin (BEL) weighing 22.1 ± 0.6 g; Berlin high (BEH+/+) weighing 59.4 ± 3.4; Berlin High without functional myostatin (BEH) weighing 65.2 ± 4.6 g. Mice age - 213 ± 69 days. Methods used - spontaneous measurement of physical activity in cage from above (TopScan Lite, Clever System), measurement of activity in a cage with a running wheel, study of behavior in new environment (File box / Hole board test) and Lashley III maze learning for cognitive function and memory retention. In most experiments, statistically significant differences were found between the heaviest and the lightest mouse strains lines (DUH vs. BEL). Conclusions: 1. The lightest mice (BEL strain) were the least active in the new environment. 2. The heaviest mouse line (DUH) showed better results of learning a maze on all days comparing to lightest mouse line (BEL). Also a moderate to strong correlation was found between body weight and Lashley III maze learning. 3. Body and muscle mass were not linked to mice activity in cage. 4. The spontaneous activity in the running wheel of the heaviest mouse strain was significantly higher compared to the lightest strain on all days of the experiment