The main purpose of this study was to investigate the effects of treadmill exercise and bright light exposure on serotonin expression in rat brain. Male Sprague-Dawley (SD) rats were randomly assigned into four groups (n=9 in each group), specifically, control group (CG), exercise group (EG), light group (LG), and exercise+light group (ELG). Rats in EG were subjected to treadmill exercise (5 days/week, 30 min/day), LG rats exposed (5 days/week, 30 min/day, 10,000 Lux), ELG rats subjected to treadmill exercise in combination with exposure, and CG rats remained sedentary over a four-week period. We observed a significant increase in serotonin expression in the raphe obscurus nucleu and the midbrain of rats in EG, LG, and ELG, compared to CG. Interestingly, serotonin expression was significantly increased in ELG, compared to EG and LG in the raphe obscurus nucleu via immunohistochemistry. In the western blot, it showed a increased pattern in ELG, compared to EG and LG. The overall results showed that treadmill exercise and/or bright light had positive effects on serotonin expression in the brain. Therefore, we suggest that moderate exercise or exposure to bright light during a growth child may be beneficial in brain action.
