Objective To explore the effects and possible mechanism of Mongolian medicine Eridun·Wurile (EW) on neuronal apoptosis in rats with acute spinal cord injury(SCI).
Methods The male SD rats were randomly divided into sham-operated group(sham group), SCI group, EW low-dose group, EW medium-dose group, EW high-dose group and EW high dose+AG490 group, with 15 rats in each group, and the SCI model of rats was established by Allen's method. EW low-dose group, EW medium-dose group and EW high-dose group were given EW suspension at a dosage of 0.32, 0.63 and 1.26 g/kg for gavage after surgery, respectively; the EW high-dose+AG490 group was given Janus kinase 2 (JAK2) inhibitor AG490 (5 mg/kg) by gavage before surgery and EW (1.26 g/kg) by gavage after surgery; and the sham and SCI groups were given equal volume of distilled water, twice a day for 2 weeks. The hind limb motor function of each group was assessed by BBB grading score at 1 day, 3, 7 and 14 days postoperatively; the rats were executed 12 h after the last administration and the spinal cord water content was examined; the histopathological changes were observed by Hematoxylin-Eosin (HE) staining in the spinal cord of each group; the apoptosis of spinal neurons was detected by in situ notch end labeling (TUNEL). The expression of Cleaved caspase-3, B-lymphoblastoma-2 (Bcl-2), Bcl-2 associated X protein (Bax), phosphorylated (p)-JAK2, and p-signal transduction and transcriptional activator 3 (STAT3) proteins in spinal cord were detected by Western blot.
Results Compared with the sham group, the BBB scores of rats in the SCI group were significantly lower, spinal cord edema and pathological structural damage were severe, the number of apoptotic cells and the expression of Cleaved caspase-3, Bax, p-JAK2 and p-STAT3 proteins in the spinal cord were significantly increased, while the expression of Bcl-2 was decreased (P < 0.05 or P < 0.01); compared with the SCI group, the BBB scores of EW low-dose group, EW medium-dose group and EW high-dose group gradually increased, the pathological injury degree of spinal cord tissue was relieved, and the number of apoptotic cells in spinal cord tissue was reduced, Cleaved caspase-3, Bax, p-JAK2, and p-STAT3 protein expressions were gradually down-regulated, while Bcl-2 protein expression was gradually up-regulated (P < 0.05 or P < 0.01); compared with EW high-dose group, the expression of P-JAK2, p-STAT3, Bax, Cleaved caspase-3 proteins down-regulated in the spinal cord tissue of EW high dose+AG490 group, and Bcl-2 protein were up-regulated, and the differences were statistically significant (P < 0.01).
Conclusion EW plays a neuroprotective role via inhibiting JAK2/STAT3 signaling pathway and reducing apoptosis in acute spinal cord injury rats.
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