Comparative study of treadmill and swimming exercises on spinal regeneration and reactive astrocytes in the brain after spinal cord injury

The purpose of this study is to compare the effects of treadmill and swimming exercise on cell survival and reactive astrogliosis in the spinal cord and brain after spinal cord injury (SCI). Thirty-two male rats were randomly assigned to four groups: the normal group (Norm, n=8), the SCI+sedentary group (Seden, n=8), the SCI+treadmill exercise group (Tread, n=8), and the SCI+swimming exercise group (Swim, n=8). All rats in the SCI groups were allowed to recover for 2 weeks after injury, and then underwent 4 weeks of low-intensity treadmill and swimming exercise. In the spinal cord, both exercise interventions decreased the cavity formation around the injury, and significantly increased induction levels of growth associated protein-43, with greater improvements in the Tread group. In the motor cortex and hippocampus of the brain, the Tread group upregulated B-cell leukemia/lymphoma 2 and downregulated cleaved-caspase-3 and glial fibrillary acidic protein relative to the Seden group, indicating enhanced cell survival and reduced reactive astrogliosis in the injury site. Compared with swimming, treadmill exercise further improved tissue preservation and neural circuit-level recovery across the spinal cord, motor cortex, and hippocampus after SCI. Thus, our findings suggested evidence that treadmill exercise might be one of the rehabilitation strategies to support the spinal cord and brain after SCI.