The expression of mitophagy protein and apoptosis factor in spinal cord injury in rats

English Keywords:Spinal cord injury  Mitophagy  Apoptosis

English Abstract:

  【Abstract】 Objectives: To investigate the mitophagy protein and apoptosis after spinal cord injury in animal models by the Allen′s method. Methods: 50 SD male rats were randomly divided into injury group and control group. The injury group was divided into 5 different time points(1h, 6h, 24h, 48h, 72h), each group had 7 rats. At different time points after injury, the rats were sacrificed and selected the injured area about 1cm long. Then the expression levels of mitophagy(LC3, NIX) and apoptosis protein(BNIP3, cleaved caspase-3, cytochrome c) were tested by Western blot. Another 4 rats at 24h after injury were used to observe neuron autophagy by transmission electron microscopy. The control group accepted no treatment, in which 7 rats were used for Western blot analysis, 4 rats were used for electron microscopy. Results: The LC3 expression in control group and at 1h, 6h, 24h, 48h, 72h after injury was 0.2893±0.0325, 0.3002±0.0474, 0.3943±0.1154, 0.4818±0.0426, 0.5430±0.0865, 0.5790±0.0892, respectively. The NIX expression was 0.1392±0.0171, 0.1431±0.0325, 0.1955±0.1379, 0.3841±0.1136, 0.4043±0.1059, 0.4506±0.0174, respectively. The BNIP3 expression was 0.1354±0.0547, 0.1896±0.1264, 0.2654±0.1341, 0.7220±0.1030, 0.4713±0.1041, 0.3975±0.1505, respectively. The cleaved caspase-3 expression was 0.2806±0.0999, 0.4158±0.1137, 0.7865±0.4056, 0.9354±0.2659, 1.0152±0.3441, 1.1608±0.2488, respectively. The cytochrome c expression was 0.1489±0.0300, 0.2196±0.0762, 0.3162±0.1656, 0.4456±0.1180, 0.5407±0.1029, 0.5812±0.1388, respectively. The protein expressions of LC3, NIX, cleaved caspase-3 and cytochrome c in 24h, 48h, 72h model group significantly increased compared with those in control group（P<0.05）. The protein expression of BNIP3 in 24h, 48h model group significantly increased compared with that in control group（P<0.05）. The ultrastructure of cells was observed by transmission electron microscope after 24h. The double membrane structure of autophagy was observed covered with damaged mitochondria and other organelles. Conclusions: After acute spinal cord injury, rats may promote mitophagy and reduce apoptosis by promoting the binding of NIX protein to LC3 and thus play a protective role in the repair of spinal cord injury.