Abstract
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.
Key words
exercise - chronic mild stress - monoamine neurotransmitters
