Naringin treatment improves functional recovery by increasing BDNF and VEGF expression, inhibiting neuronal apoptosis after spinal cord injury.

The aim of this study was to determine the therapeutic efficacy of starting naringin treatment 1 day after spinal cord injury (SCI) in rat and to investigate the underlying mechanism. SCI was induced using the modified weight-drop method in Sprague-Dawley rats. The SCI animals were randomly divided into three groups: vehicle-treated group; 20 mg/kg naringin-treated group; 40 mg/kg naringin-treated group, and additionally with sham group (laminectomy only). Locomotors functional recovery was assessed during the 6 weeks post operation period by performing open-field locomotors tests and inclined-plane tests. At the end of the study, the segments of spinal cord encompassing the injury site were removed for histopathological analysis. Immunohistochemistry was performed to observe the expression of the brain-derived neurotrophic factor (BDNF). The expression of vascular endothelial growth factor (VEGF), B-cell CLL/lymphoma-2 (Bcl-2), BCL-2-associated X protein (Bax) and caspase-3 were detected by Western blot analysis. The apoptotic neural cells were assessed using the TUNEL method. The results showed that the naringin-treated animals had significantly better locomotor function recovery, less myelin loss, and higher expression of BDNF and VEGF. In addition, naringin treatment significantly increased in Bcl-2:Bax ratio, reduced the enzyme activity of caspase-3 and decreased the number of apoptotic cells after SCI. These findings suggest that naringin treatment starting 1 day after SCI can significantly improve locomotor recovery, and this neuroprotective effect may be related to the upregulation of BDNF and VEGF and the inhibition of neural apoptosis. Therefore, naringin may be useful as a promising therapeutic agent for SCI.