| Objective:Observe the apoptosis of acute spinal cord injury treated by methyldnisolone. To explore MP whether have the function of anti-apoptosis in treat ASCI. Detected some factors activities like caspase-3,6,8,9which closely related apoptosis. Analysis the possible mechanisms of ASCI treated by MP.Methods:1. The acute spinal cord injury models were made according to Allen's weight-drop method. All animals were divided randomly into 3 groups:sham group (group S, 12 rabbits), control group (group C,36 rabbits) and treatment group (group T, 36 rabbits). Evaluate spinal cord motor nerve functions by Rivlin loxotic plate scores and BBB Scoring system in different time points. Compare and analysis differences during groups.2. From group C and T, 3 rabbits were selected randomly and sacrificed to harvest the contused about 1.5cm long spinal cord tissue at each time point of 8, 24, 72 hours and 7, 14, 28 days following SCI. Samples were harvested from each rabbit. Six continuous histological sections of 10μm thickness were made through microtomy from the central of each sample.3 sections were prepared for HE staining (Hematoxylin-eosin staining) to observe the pathological changes.3. Three sections were prepared for TUNEL (terminal-deoxynueleotidyl transferase mediated nick end labeling) test to observe and count the apoptotic cells in microscopy.4. Detected some factors's activities which closely related apoptosis like caspase-3,6,8,9. Analysis statistically significant during the groups.Results:1. The mean of loxotic plate critical degrees and BBB scores were gradually increased in all groups. The means of degrees and scores of group T were more than group C. There were significant differences both in loxotic plate critical degrees and BBB scores at 7, 14 and 28 days following SCI between group C and T (P<0.05).2. Group S have no change in pathological by HE staining. Spinal cord tissue lost the structure, there were varying degrees edema and necrosis of never cells, vacuoles in gray matter, neutrophils and bleeding in necrotic area both in group C and T. There were no significant differences between two groups in 8, 24 and 72 hours following SCI. Group T have better recovery than group C at the time points in 7, 14, 28days. There have significant differences between two groups.3. There weren't found apoptosis in group S tested by TUNEL. Apoptotic cells were found in group C and T at 8 hours later, to the peak at 24 hours of following SCI,3 days later there were still many positive cells. Apoptotic cells gradually decreased at 7 days after SCI. There were significant difference of apoptotic cells between group C and T in those four time points (P<0.05). There were no difference between group C and T at 14, 28days after SCI (P>0.05).4. Activities of Caspase-9 were too low to detect in the group S. Activities of Caspase-3,6,8 were all very little. The activities of all caspase factors were increased at 8hours later of SCI, 24 hours to the peak, 3 days later there still have high activities. The activities decreased gradually after 7days and decreased significantly after 14days later of SCI. There were significant difference of the activities of Caspase-3,6,8,9 between group C and T in those four time point(P<0.05). There were no difference between two groups at 14 days and 28 days after SCI(P>0.05).Conclusion:1. Spinal cord motor nerve functions have significant improved in the acute spinal cord injury animal model treated by methylprednisolone;2. Methylprednisolone have mitigation to the secondary spinal cord injury;3. Methylprednisolone have anti-apoptosis in the treatment of acute spinal cord injury;4. Anti-apoptotic effects may be caused by MP inhibit the activities of Caspase-3,6,8,9 in the treatment of ASCI.
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