| Objective:To investigate expression of CHOP/GADD153(C/EBP homologous protein/growth arrest-and DNA damage inducible gene 153) in acute spinal cord injured rats which were treated with Melatonin,to explore its protection and mechanism in the spinal cord injury.Methods:Rat model of ASCI was established with a modified Allen's method that the metal stick of lOg failed into the spinal cord (T9-T10)from the height of 2.5CM. Sprague Dawley rats(n=96) were injured with this method and then randomly divided into three large group:group MT(ASCI with MT injection,n=32), group Alcohol(ASCI with Alcohol injection,n=32) and group NS(ASCI with NS injection, n=32). Every large group was also divided into four small groups according to the sacrificed time. Every 8 rats from each group were sacrificed at 3h,1d,3d,7d respectively after injury. The neurofunction of the spinal cord was evaluated by modified Tarlov score before sacrifice. Cell apoptosis was examined by using the TUNEL assay and the expression of CHOP was detected by using immunohistochemistry method.The expression of CHOP and cell apoptosis was measured by using of Motic.med 6.0 with IOD(integrated optical density)and Apoptosis Index(AI).Results: The Tarlov scores of group MT, group AC and group NS were separately:3h2.82±0.12,2.68±0.21and2.71±0.17;1d 2.68±0.06,2.58±0.06and2.52±0.19; 3d 2.60±0.37,2.37±0.11and2.38±0.12; 7d3.51±0.08, 2.85±0.04and2.80±0.10. The group MT was much better than group AC and group NS except at the 3-hour-point, and there was significant difference(P<0.05), especially the modify of the nerofunction in the group MT after the 3-day-point.There is no significant difference between group AC and group NS at every time-point.The expression of CHOP was posotive in the spinal tissue of every group,compared with group AC and group NS, group MT had no significant difference between them at the 3-hour-point,but much lower at every other point,and had significant difference. There was no significant difference between group AC and group NS. In group MT, there was significant difference betweeen 3h,1d,3d and 7d groups (p<0.05) and the CHOP expression was 3h7d. The apoptotic cells were first examined at 3-hour-point in group MT,group AC and group NS. They all got the peak at 3d and began to decreased at 7d. Compared with Group AC and Group NS, The Apoptotic index was much lower in Group MT except at the 3-hour-point and had significant difference, there was no significant difference between group AC and group NS at every time-point. In group MT, the Apoptotic index had significant difference at every time point: 3h<1d<3d>7d.Conclusion:1. Rat model of ASCI was successfully established with a modified Allen's method in this research.2.MT had protective function in the acute spinal cord injury and improved neural function, this may related to its significant inhibition of the expression of CHOP and the aptoposis of neurocyte.3. The efficiency of MT for improving neural function of injured spinal cord maybe related to its treatment time.4.5%Alcohol and NS can not improved neural function in the acute spinal cord injury. |
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