Exercise intervention may prevent depression.

Physical activity is an effective component of depression management. However, the mechanisms by which exercise affects behavioral disorders remain unclear. The present study was conducted to investigate mechanisms by which voluntary exercise ameliorates depression. Plasma cortisol levels and hippocampal monoamine neurotransmitters were measured. Chronic mild stress (CMS) was used to induce depression in a rat model. The rats were allowed to swim for 10 weeks as part of their exercise treatment. Depressive behavior was analyzed using an open-field test and a sucrose consumption test before and after exercise. Serum cortisol levels were measured by radioimmunoassay. The concentrations of monoamine neurotransmitters in the hippocampus were determined using high-performance liquid chromatography with electrochemical detection. The CMS rats showed behavioral improvement after exercise. Compared with the control, serum cortisol levels were significantly increased by CMS. The serotonin, dopamine, and norepinephrine levels in the hippocampi were significantly increased by exercise. These findings indicate that exercise reverses and prevents the decrease in serotonin and noradrenaline, and restores dopamine in the CMS model.