Combined effects of treadmill exercise and naringenin treatment on neuronal survival and corticospinal tract fibers sprouting after spinal cord injury

The purpose of this study was to investigate the combined effects of treadmill exercise and naringenin treatment on neuronal survival and corticospinal tract (CST) fibers sprouting following spinal cord injury (SCI). Forty male rats were randomly assigned to four groups (n=10 in each group): the normal group (Norm), the SCI+sedentary group (SCI+S), the SCI+naringenin group (SCI+Na), and the SCI+naringenin combined with exercise group (SCI+Na+Ex, n=10). All rats in the SCI were allowed to recover for 2 weeks after injury, and the exercise group subsequently underwent 4 weeks of low-intensity treadmill exercise. Histological and molecular analyses were performed to evaluate astrocyte activation in the dorsal region, neuronal survival in the ventral horn, and axonal elongation in the caudal CST fibers following SCI. As a result, in the dorsal region of the injury site, both treatment groups showed significantly increased glial fibrillary acidic protein expression compared to the SCI+S group, indicating enhanced astrocyte activation. In particular, the SCI+Na+Ex group demonstrated prominent astrocytic infiltration into the cavity. In the ventral horn of the injured spinal cord, the number of mo-tor neurons was significantly preserved in the SCI+Na+Ex group com-pared to the SCI+S group. In the caudal CST, the SCI+Na+Ex group exhibited significantly increased neurofilament-200 expression, suggest-ing enhanced axonal regeneration. Furthermore, regeneration-associated proteins including growth-associated protein-43 and activating transcription factor-3 were significantly increased following the combined intervention. Combined treatment of treadmill exercise and naringenin might be one of the rehabilitation strategies to promote neural recovery after SCI.