Rhein lysinate improves motor function in rats with spinal cord injury via inhibiting p38 MAPK pathway

The current study aims to investigate the effect of rhein lysinate (RHL) on neuromotor function in rats with spinal cord injury (SCI) and to explore the underlying mechanism. A total of 63 adult male SD rats were randomly divided into the sham group, SCI group and RHL group (SCI-RHL group), with 21 rats in each group. Basso Beattie Bresnahan (BBB) scoring and the inclined plate test were used to evaluate the changes in motor function after SCI. Then, superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and malondialdehyde (MDA) contents were quantified. Caspase-3-positive cells in spinal cord tissue were detected by immunohistochemical (IHC) staining, and protein expression was detected by Western blots. Here, our data showed that compared with the SCI group, the BBB score and inclined plate test score of the SCI-RHL group were significantly higher than those of the SCI group 7 days after the RHL intervention. After 7 days of RHL treatment, the activities of SOD and GSH-Px in the spinal cord increased significantly. At the same time, RHL reduced the MDA content in spinal cord tissue of SCI rats. Moreover, cleaved-caspase-3-positive cells and apoptotic cells were significantly lower in the SCI-RHL group than in the SCI group. More importantly, p38 mitogen-activated protein kinase (p38 MAPK) was significantly decreased in the SCI-RHL group compared with the SCI group. In summary, RHL can inhibit the activation of the p38 MAPK pathway after SCI, thereby reducing the apoptosis of spinal cord neurons and improving the neuromotor function of SCI rats.