Objective To investigate the effect and mechanism of total paeony glycosides(TPG)on spinal cord apoptosis in rats with spinal cord injury(SCI).Methods A total of 18 SD rats were randomly divided into control group,SCI group and TPG group(6 each).The SCI rat model was established using Allen method.For rats in control group,the spinal cord was sutured directly after laminectomy without spinal cord injury;those in TPG group were intraperitoneally injected with 25 mg/kg TPG every 24 hours after the establishment of SCI model,while those in SCI group and control group were intraperitoneally injected with the same volume of normal saline for 28 days.The rats'behavioral score were evaluated using Basso-Beattie-Bresnahan(BBB)method.The apoptosis of spinal cord cells was measured by flow cytometry.Western blotting was performed to detect the expression levels of cell apoptotic protein cleaved caspase-3 and cleaved caspase-9.The contents of MDA,SOD and LDH in the supernatant of spinal fluid were quantified with corresponding kits.Results Compared to those in control group,the BBB score decreased significantly,while the apoptosis rate of spinal cord cells and the expression levels of cleaved caspase-3 and cleaved caspase-9 were obviously elevated,and the contents of MDA and LDH increased,SOD decreased in the supernatant of spinal fluid in the rats of SCI group(P<0.05).Compared to those in SCI group,after treatment with TPG,the BBB score increased significantly,the apoptosis rate of spinal cord cells and the expression levels of cleaved caspase-3 and cleaved caspase-9 decreased obviously,while the contents of MDA and LDH decreased,and SOD increased in the supernatant of spinal fluid of the rats in SCI group(P<0.05).Conclusion TPG inhibits the apoptosis of spinal cord cells in SCI rats,which may related to the function of TPG in regulating oxidative stress.