Treadmill exercise alleviates chronic mild stress-induced depression in rats

Depression is a major cause of disability and one of the most common public health problems. In the present study, antidepressive effect of treadmill exercise on chronic mild stress (CMS)-induced depression in rats was investigated. For this, sucrose intake test, immunohistochem-istry for 5-bromo-2’-deoxyuridine, terminal deoxynucleotidyl transfer-ase-mediated dUTP nick end-labeling staining, and Western blot analy-sis for brain-derived neurotrophic factor, cyclic adenosine monophos-phate response element binding protein, and endothelial nitric oxide synthase were conducted. Following adaptation to the animal vivarium and two baseline fluid intake tests, the animals were divided into four groups: the control group, the CMS-induced depression group, the CMS-induced depression and exercise group, and the CMS-induced depression and fluoxetine-treated group. The animals in the CMS groups were exposed to the CMS conditions for 8 weeks and those in the control group were exposed to the control conditions for 8 weeks. After 4 weeks of CMS, the rats in the CMS-induced depression and ex-ercise group were made to run on a motorized treadmill for 30 min once a day for 4 weeks. In the present results, treadmill exercise alleviated CMS-induced depressive symptoms. Treadmill exercise restored su-crose consumption, increased cell proliferation, and decreased apop-totic cell death. The present results suggest the possibility that exercise may improve symptoms of depression.