title: Treadmill exercise reduces spinal cord injury-induced apoptosis by activating the PI3K/Akt pathway in rats.
abstract: Apoptosis occurring secondary to spinal cord injury (SCI) causes further neural damage and functional loss. In this study, a rat model was used to investigate the effect of treadmill exercise on SCI-induced apoptosis and expression of neurotrophic factors. To produce SCI, a contusion injury (10 g × 25 mm) was applied subsequent to laminectomy at the T9-T10 level. Following SCI, treadmill exercise was performed for six weeks. Hindlimb motor function was evaluated with a grid-walking test. The expression of neurotrophic factors and the level of apoptosis at the site of SCI were determined by western blotting. SCI reduced hindlimb motor function and suppressed expression of neurotrophin (NT)-3 and insulin-like growth factor (IGF)-1. Expression of phosphatidylinositol 3-kinase (PI3K), the ratio of phosphorylated Akt to Akt (pAkt/Akt) and the ratio of B-cell lymphoma 2 (Bcl-2) to Bax (Bcl-2/Bax) were decreased, and cleaved caspase-3 expression was increased by SCI. Treadmill exercise enhanced hindlimb motor function and increased expression of nerve growth factor (NGF), NT-3 and IGF-1 in the SCI rats. Treadmill exercise increased PI3K expression, the pAkt/Akt and the Bcl-2/Bax ratios, and suppressed cleaved caspase-3 expression in the injured spinal cord. This study demonstrated that treadmill exercise promotes the recovery of motor function by suppressing apoptosis in the injured spinal cord. The beneficial effect of exercise may be attributed to the increase in expression of neurotrophic factors via activation of the PI3K/Akt pathway.
authors: Department of Physiology, College of Medicine, Kyung Hee University, Seoul 136-701, Republic of Korea.
authors: Sun-Young
authors: SY
authors: Jung
authors: Department of Physiology, College of Medicine, Kyung Hee University, Seoul 136-701, Republic of Korea.
authors: Dae-Young
authors: DY
authors: Kim
authors: Department of Biochemistry and Molecular Biology, Age-Related and Brain Diseases Research Centre, College of Medicine, Kyung Hee University, Seoul 136-701, Republic of Korea.
authors: Tae Young
authors: TY
authors: Yune
authors: Department of Food and Biotechnology, Graduate School of Life Sciences and Biotechnology, Korea University, Seoul 136-701, Republic of Korea.
authors: Dong-Hoon
authors: DH
authors: Shin
authors: Department of Psychiatry, Gangneung Asan Hospital, Ulsan University, Gangneung 210-711, Republic of Korea.
authors: Sang-Bin
authors: SB
authors: Baek
authors: Department of Physiology, College of Medicine, Kyung Hee University, Seoul 136-701, Republic of Korea.
authors: Chang-Ju
authors: CJ
authors: Kim
keywords: apoptosis; motor function; neurotrophic factors; spinal cord injury; treadmill exercise