Effect of exercise on hyperactivity, impulsivity and dopamine D2 receptor expression in the substantia nigra and striatum of spontaneous hypertensive rats

PURPOSE Attention-deficit/hyperactivity disorder (ADHD) is a heritable, chronic, neurobehavioral disorder that is characterized by hyperactivity, inattention, and impulsivity. It is commonly believed that the symptoms of ADHD are closely associated with hypo-function of the dopamine system. Dopamine D2 receptor activation decreases the excitability of dopamine neurons, as well as the release of dopamine. Physical exercise is known to improve structural and functional impairments in neuropsychiatric disorders. We investigated the therapeutic effect of exercise on ADHD. METHODS Open field task and elevated-plus maze task were used in the evaluation of hyperactivity and impulsivity, respectively. Dopamine D2 receptor expression in the substantia nigra and striatum were evaluated by western blotting. RESULTS The present results indicated that ADHD rats showed hyperactivity and impulsivity. Dopamine D2 receptor expression in the substantia nigra and striatum were increased in ADHD rats. Exercise alleviated hyperactivity and impulsivity in ADHD rats. Furthermore, dopamine D2 receptor expression in ADHD rats was also decreased by exercise. CONCLUSION We thus showed that exercise effectively alleviates ADHD-induced symptoms through enhancing dopamine D2 expression in the brain.