| Background and ObjectiveAs a part of the central nervous system, the spinal cord is not only a junior centrum controling body movement, feeling, internal activity,but also but also is a key structure communicating the brain with peripheral nervous system, where there are dense fasciculuses. So even there is a focal injury to the spinal cord, it can induce a severe result such as permanent paralysis, feeling function losing, defecation function disturbance and vegetative nerve functional disturbance. So the morbidity of death and deformity in spinal cord injury is very high, which bring great economy and psychological burden. But protection and restoration of nerve function after spinal cord injury for medicine is still a big problem in the world. Although it is not totally conquered, some progress has been also made through tireless efforts of scientists in the past few decades. Studies have shown that nerve cells will quickly generate heat shock protein after stimulation and HSP27 of nerve cells can play protective effect through various mechanisms. Many factors can cause nerve cells to produce HSP27, but these methods are still unable to be used in clinical applications.It will have important practical significance in clinical treatment of spinal cord injury if HSP27 is induced by drugs in the spinal cord of expression.Methylprednisolone is only medicine used in clinic approved by FDA. Research shows that it can raise HSP27 expression to protect spinal nerve cell. After U.S. three national acute spinal cord injury study, the standard therapy in the world has been widely applied in acute spinal cord injury.But there is much SCII(Spinal Cord ischemia-reperfusion Injury) phenomenon in clinic, spinal cord ischemia-reperfusion injury can appear after decompression surgery such as severe spinal cord of cervical spondylosis, thoracic spinal stenosis. If the application of MP can effectively reduce ischemia-reperfusion for spinal cord injury, the treatment of spinal column diseases is a very big progress.But there is not a unified standard for MP usage in treatment of spinal cord ischemic reperfusion injury, clinical and scientific researchers are also exploring the application. Some people has found that the best time of using MP in treatment of SCâ…¡, but the best dose has not been reported.This study is to discover the better MP dose of protecting spinal cord by inducing the expression of HSP27 through such methods as making animal models of spinal cord ischemia-reperfusion injury, using different doses of Methylprednisolone within 30 minutes before SCâ…¡,detecting the expression of the HSP27 of rats'spinal cord by immunohistochemstryMethods100 ordinary rats were randomly divided into five groups (n=20):Group A,B,C,D and E, normal group,SCâ…¡group,MP treatment groups (three different doses ).we obstructed the abdominal aorta between the left and the right renal artery for 30min and let it receive reperfusion after 3h to make the SCâ…¡model.At 30min prior to injury, the rats in C, D and E group received 10mg/kg,20mg/kg,30mg/kgMP respectively.And the rats in group B received the same dose of normal saline as control before injury. The spinal cord specimen from group A 3h after surgery and from other groups 3h after injury were taken out and cut ,then the pathological changes of spinal cord cells with HE staining and the expression of Hsp27 in spinal cord cells with immunohistochemical staining were observed respectively. The data were analysed with SPSS 13.0 soft ware.Results1. There were significantly edema, degeneration, necrosis and so on in spinal cord after SCâ…¡in rats2. The expression of HSP27 showed weak positive in the normal group and obviouly increased in SCâ…¡group.3. The secondary injury of spinal cord was significantly improved in MP group. The expression of HSP27 significantly increased and showed strong positive.4. In the expression of HSP27,there was a significant difference among each group in total (P<0.05); There was significant statistical difference between group B and group A(P<0.05). NO significant statistical difference was found in the expression between group B and group C (P>0.05). There was significant statistical difference between group D and group C (P<0.05) and also statistical significance was found between group E and group D (P<0.05).Conclucions1. The pathological morphology of spinal cord can be obviously improved when preventive using MP before SCâ…¡, and it appears that early using MP before SCâ…¡has certain protective effect to some protective effect.2. HSP27 expression is weak positive in normal spinal nerve cells and is up-regulated after SCâ…¡,but its expression will be up-regulated significantly when using MP at 30min prior to injury.3. HSP27 expression is up-regulated at different levels when using different doses MP prior to injury, and 30mg/kg MP is the best dose.
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