Relationship Between Aerobic Exercise Capacity And Behavior Disorders In Mice

Cardiac output is a critical determinant of aerobic exercise capacity, influencing both physical performance and, intriguingly, brain functions. Despite the known impact of heart function on mood regulation, the connection between inherent cardiovascular endurance and susceptibility to behavioral disorders remains elusive. PURPOSE: To examine the association between basal aerobic exercise capacity and the manifestation of depressive-like behavior in mice. Specifically, phenotypes defined by heightened anhedonia, helplessness, and low motivation. METHODS: In this quantitative experiment, 20 C57BL/6 mice were classified into low and high aerobic performance groups containing 5 females and 5 males each. Animal selection was based on running ability of 36 mice subjected to a maximum aerobic capacity test without prior training. The low and high performing groups ran less than 180 min and over 250 min, respectively. The mice underwent a sucrose preference test (SPT), measuring anhedonia, and a tail suspension test (TST), assessing motivation and helplessness, 48 h post-treadmill test. Behavioral analysis was complemented with cardiac morphological measures using ultrasound and brain fluorescent imaging conducted the next day. Two-tailed independent T-tests compared data between groups. RESULTS: Data showed no significant difference in anhedonia between the high and low aerobic performance groups (78.87 ± 9.55 vs. 79.15 ± 6.18%, p > 0.05). The mean TST immobility ratio did not differ significantly between poor and good runners (37.77 ± 12.67 vs. 43.13 ± 15.16%, p > 0.05), revealing no variation in expressed motivation between groups. The mean ejection fraction (%) for low and high-performance running groups suggested no discrepancy in cardiac output for different aerobic fitness levels (34.08 ± 10.96 vs. 29.87 ± 10.69%, p > 0.05). Brain perfusion measured by mean arrival time of fluorescent dye to the brain was not significantly different between low and high aerobic capacity groups (1.42 ± 0.15 vs. 1.57 ± 0.23 sec, p > 0.05). No difference was seen between males and females (p > 0.05). CONCLUSION: Aerobic exercise capacity does not relate to different behavioral phenotypes in mice. Future testing includes looking at the long-term effects of aerobic training, rather than basal aerobic endurance, on behavior.