Dopamine D2 Receptor Genotypes And Physical Activity Levels

Abstract

PURPOSE Dopamine influences physical activity via effects on motor control and motivation. Reduced D2 density has been associated with reduced physical activity. The DRD2 A1 allele is associated with reduced D2 receptors; therefore, this genotype may be associated with a more sedentary lifestyle. We examined the relationship between DRD2 genotypes and objectively measured physical activity and physical fitness. METHODS 31 adult subjects (18 males- mean age 45y; 13 females-mean age 48y) who had DRD2genotyping performed a submaximal cycle ergometer test to estimate aerobic fitness. Subjects walked on a treadmill wearing an accelerometer at an exercise intensity of 3 Mets to determine the accelerometer g value associated with each subject's moderate to vigorous physical activity level (MVPA, ≥3 Mets). They then wore the accelerometers for 2 weekdays and one weekend day to determine free-living physical activity levels. Group differences in physical activity and aerobic fitness were analyzed using a 2 sex × 2 genotype ANOVA. RESULTS Females with an A1 allele engaged in 33% less physical activity than females without an A1 allele (866.2±120.0 vs. 1291.0±96.0 min, p=0.01) due to less low intensity (< 3 Mets) physical activity (766.8±100.9 vs. 1150.1±80.1 min, p=0.005). There was no effect of genotype on MVPA or fitness in females. There was no effect of DRD2 genotype on male total activity time, low intensity physical activity, MVPA or fitness. CONCLUSIONS Females with a dopamine D2 receptor genotype that is associated with fewer D2 receptors have lower objectively measured physical activity levels than females with a genotype associated with a greater number of D2 receptors.