Effect of Shionone on Neuron Apoptosis After Spinal Cord Injury in Mice

Abstract

Objective To explore the effect of shionone(SHI)on motor function in the mouse model of spinal cord injury(SCI)and probe into the underlying molecular mechanism. Methods C57BL/6 mice were treated to induce the SCI model and then assigned into a model group(SCI group),a SCI+SHI group,and a sham surgery(control)group.The Basso mouse scale(BMS)score was determined to evaluate the recovery of motor function in SCI mice.Hematoxylin-eosin(HE)staining,Nissl staining,and immunofluorescence staining were employed to examine the fibrosis,morphological changes of neurons,and neuron apoptosis in the spinal cord tissue of SCI mice,respectively.The mouse hippocampal neuronal cell line HT22 was cultured in vitro and then classified into tumor necrosis factor α(TNF-α)induction and SHI groups.Western blotting was employed to determine the expression of apoptosis-associated proteins.Network pharmacology,gene ontology annotation,and Kyoto Encyclopedia of Genes and Genomes pathway enrichment were employed to predict the possible molecular targets and signaling pathways of SHI in promoting functional recovery from SCI.Furthermore,the prediction results were verified by in vitro and in vivo experiments. Results Compared with the SCI group,the SCI+SHI group showed increased BMS score on days 21,28,35,and 42(P=0.003,P=0.004,P=0.023,and P=0.007,respectively),reduced area of spinal cord fibrosis(P=0.021),increased neurons survived(P=0.001),and down-regulated expression of cleaved cysteine aspastic acid-specific protease 3(cleaved Caspase-3)(P=0.017).Compared with the TNF-α group,the SHI group presented down-regulated expression levels of cleaved Caspase-3 and Bax(P=0.010,P=0.001)and up-regulated expression level of Bcl-2(P=0.001).The results of bioinformatics analysis showed that SHI might improve the motor function of SCI mice via the phosphatidylinositol 3-kinase/protein kinase B(PI3K/Akt)signaling pathway.The results of in vivo and in vitro experiments showed that SHI inhibited the phosphorylation of PI3K and Akt in SCI mice or HT22 cells exposed to TNF-α(all P<0.05).The number of apoptotic HT22 cells after treatment with insulin-like growth factor 1 was higher than that in the SHI group(P=0.003). Conclusion SHI may inhibit neuron apoptosis via the PI3K/Akt signaling pathway,thereby promoting the recovery of motor function in SCI mice.