Establishment Of A Mouse Model Of Allen's Spinal Cord Injury And Study Initially The Expression Of Zinc Finger Protein A20 Of Mouse Myeliod Tissues In The Process Of Spinal Cord Injury With Infection

As the development of industry, agriculture, architecture and transportation, the incidence of spinal cord injury (SCI) is on the tendency of increasing gradually. The functional lesion such as paraplegina caused by SCI not only brings enormous physically and mentally painful to the patient himself, but also spell heavy economic burden and social problem to the family and society. At present, the investigative procession of SCI is relatively slow that the prognosis is hard to estimate, as the pahophysiological mechanism of SCI is so complicated that we haven't completely recognize it. So establishing an eligible SCI model is the prerequisite for SCI foundmental investigate. Allen has report the model of vertical coup to the injury in 1911, which was more close to mankind spinal cord injury process and had good clinical dependability. It is widely used in SCI study and treatment. Now, rat acute SCI model is applied extensive, as well as to make tremendous contribution to human SCI therapeutic research. But to accompany with the research of SCI, it becomes more and more important to explore the importance of one certain gene or cytokine related to the prognosis. Mice is not only low cost, easy to feeding, but also has more predominace in genetic research aspect. It's relatively easy for us to analyze the importance of one certain gene or cykokine to the prognosis, because the mice's gene has high homology with mankind, and the mice genetic manipulation technique is also mature. So we establish mice acute SCI model and evaluate it.Zinc finger protein A20 is a new group developed recently in cytoendogenous protection mechanism research. The stimulating factor such as LPS or TNF can induce quick expression of endogenous zinc finger protein A20.A20 is the key to limit the secondary lesion reaction by terminating activation of NF-kB which induced by LPS or TNF. It has reverse feedback regulation effect for activation of NK-kB, and is an important endogenous modulin which can prevent an uncontrolled inflammatory reaction in vivo. The discovery of A20 has provided an original pathway to reveal organisim endogenous protection mechanism in advance and inhibited traumatic infection and the occurrence, development of its complication. But when there is SCI paraplegia complicated with endotoxemia, a trail corresponding problem such as the expressive change rule of A20 in myeloid tissue, the interrelationship with neuron secondary lesion and neuron endogenous protection mechanism under stimulatory function of endotoxin is still need of a further study and approach.OBJECTIVE1.To establish and evaluate a mouse model of graded Allen's spinal cord injury(SCI), and provide theoretical evidence for a new model of contusive SCI.2. To study initially the expression of zinc finger protein A20 of mouse myeloid tissues in the process of spinal cord injury with infection and the effect on the posttraumatic secondary endotoxic spinal cord injury.METHODS1.A total of 153 mice were divided into surgical controls (n=18)that received laminectomy but did not receive a contusive injury, and experimental groups(n=135)ruined by modified Allen's method and distinguished by the amount of weight in grams dropped onto the impounder and height from the weight to the impounder: group A(2g×2.5cm n=45), group B(3g×2.5cm n=45) and group(3g×5cm n=45).All animals were assessed by electrophysiological, structural and examined using the Basso Mouse Scale (BMS).2.The mode of SCI and SCI with infection were made.Ninty-five healthymouse of both sexes with a mean body weight of 20 g(18～22 g)were randomized into 4 groups:control,SCI,LPS and SCI plus LPS.And tested by pathohistologic observation and BMS score. RESULTSThe BMS revealed a statistically significant difference between surgical controls and experimental groups after injury. In experimental groups, there was no difference in functional outcome between group A and surgical controls after week 2; group C recovered badly with a high mortality and there was no recovery evidence in group B up to week 8. The mean peak latency of N1 wave in MEP prolonged by day 3 and then gradually decreased in experimental groups; however, by week 1 there were no significant difference between group A and surgical controls(p>0.05); in group B and C, there were still significant decrement by week 8. there were different Histopathological changes in groups at tested time.There was significant difference between SCI group and SCI plus LPS group in day 5 and day 7(p<0.05). Both control group and LPS group had no obvious congestion and hydropsia. Hematoma subsided within 3 days in SCI group. There had congestion and edema partly in day 5 in SCI plus LPS, which subsided until day 7.Neither control group nor LPS group had obvious positive expression of A20 in neural cellular kytoplasm.A20 positive expression existed in SCI group in 8h ,12h and day 1;and in SCI plus LPS group in 2h which continue to day 3.CONCLUSIONS1.A mouse model of contusive spinal cord injury is a reasonable model and provides theory basement for SCI studies. 2.Zinc finger protein A20 is highly expressed as an endogenous anti—inflammatory protein which participate the inflammatory reaction in vivo.It expressed positively in SCI alone and SCI with infection in which state its expression significantly prolong. It further indicates that expression of A20 in tissues following SCI with infection might play an important role in prevention of uncontrolled inflammatory response.