Inhibitive effects of monosialotetrahexosy 1 ganglioside on spinal cord injury-induced endoplasmic reticulum stress in rats

Objective To investigate the effects of monosialotetrahexosy 1 ganglioside (GM1) on endoplasmic reticulum stress-mediated apoptosis following spinal cord injury (SCI).Methods Ninety SD rats were randomly and equally assigned to the sham-operation group,the isotonic saline group and the GM1 group.Rat T10 SCI model was established by using Allen method in both the isotonic saline group and the GM1 group.The nerve function of spinal cord was evaluated by modified Tarlov score after the animals were scarificed at 3rd h,24th h,3rd day,and 7th day respectively after injury..The apoptosis was determined with Hochest 33658 staining.The expression of endogenous cysteinyl aspartate-specific protease (Caspase)-12 and CHOP protein was observed by fluorescence microscopy.The cell total protein was extracted for detection of the endoplasmic reticulum stress related Caspase-12 and CHOP protein expression by using Western blotting.Further at the cellular level,the apoptosis of human neuroblastoma cells (SH-SY5Y) was induced by STS (5 μmol/L),and 12 h later,the cells were added with GM1 (0,20 and 50 mmol/L),and incubated for 48 h.The expression of Caspase-12 and CHOP proteins was detected by using Western blotting,and the apoptosis rate was determined with propidium iodide (PI)/Annexin V-FITC staining by flow cytometry analysis.Results Different levels of paralysis were evidenced in the isotonic saline group and the GM1 group,but not in the sham-operation group,with the Tarlov score in the former much lower than that in the latter at each time point (P ＜ 0.01).As compared with the sham-operation group,the levels of Caspase-12 and CHOP protein expression (0.24 ±0.02 and 0.63 ±0.10) were increased (P ＜ 0.05),and the apotosis rate was reduced (P ＜ 0.05) in the isotonic saline group.As compared with the isotonic saline group,the levels of Caspase-12 and CHOP protein expression (0.13 ± 0.01 and 0.43 ± 0.07) was reduced (P ＜ 0.05),and the apoptosis rate was declined (P ＜ 0.05) in the GM1 group.After addion of GM1,the cell apoptosis rate was cut down (7.4 ± 6.9) (P ＜ 0.05),and the levels of Caspase-12 and CHOP protein expression were reduced (P ＜ 0.05).Conclusion GM1 can inhibit endoplasmic reticulum stress-mediated apoptosis following SCI by reducing the levels of Caspase-12 and CHOP protein expression. Key words: Monosialotetrahexosy 1 ganglioside; Spinal cord injury; Endoplasmic reticulum stress; Apoptosis