Establishment Of A Spinal Cord Blast Injury Model And Research Of The Apoptosis-related Genes' Expression Following The Spinal Cord Blast Injury

Objective:①To develop a small size device which generate shockwave and simulate blast injuries caused by the shock of explosion.②To establish a laboratory efficient wound model in rabbits for the study on spinal cord shockwave injury at different extents.③To observe potential changes in the Bcl-2 and Bax proteins expression in rabbit spinal cord after the blast injury, so as to provide the experimental basis for further clarifying the mechanism of spinal cord blast injury and for clinical therapy.Methods:①The device composed of the gas storage facilities, launch systems and shock wave analysis system was developed based on gas-dynamical principles, rupture of membrane and sensor detection technology. Positive pressure peak, duration and propagation velocity were detected by oscilloscope at the different pressure of gas source. Each of the gas pressure 400kPa,500kPa,600kPa,700kPa,800kPa was repeated five times.②24 New Zealand white rabbits were randomly divided into four groups of six. A group: control group; B group: gas source pressure of 0.4MPa; C group: gas source pressure of 0.6MPa; D group: gas source pressure of 0.8MPa.The rabbit's spinal cord of T9 and T10 was injured by different pressure of gas source with the device. The degrees of spinal cord shockwave injury were evaluated by histological analysis and the extent of function changes of feel and behavior were investigated after injury 48 hours.③Moderate spinal cord blast injury in rabbits were induced by the device at the gas source pressure of 0.6MPa.Light microscopy was used to observe the morphologic changes in rabbit spinal cord and immunochemical method was used to study the expression of Bcl-2 and Bax proteins in rabbit spinal cord from 4 h to 72 h after the spinal cord blast injury.Results:①The waveform detected by the shock wave analysis system of the device is similar to the Friedlander waveform, a typical air-blast waveform. With the gas source pressure, positive pressure peak and propagation velocity increase at the same time, the duration of positive pressure remain basically unchanged. Data of each group keep good reproducibility.②The motor function of rabbit hind limbs was significantly worsened duo to the stronger shockwave pressure. It was found that the damaged spinal cord area edema, degeneration and necrosis, the pathological damage to the gray matter of spinal cord was serious 48h after injury. The score of rabbit hind limb sensory and motor function was significantly different and with good reproducibility.③During the post burst phase (4～72 h),the increased necrotic and swollen cell in spinal cord was observed by light microscopy and the pathological damage to the gray matter of spinal cord was serious. After the blast injury, expressions of protein Bcl-2 and protein Bax were observed all over the spinal cord, but it was not uniform in time distribution. The expressions of protein Bcl-2 were observed 12h after the spinal cord blast injury and reached peak value during 24h～48h. The expressions of protein Bax were observed 4h after the spinal cord blast injury and the degree of the expressions was stronger than protein Bcl-2.Conclusion:①The device we developed can simulate the shockwave generation. It was safe and functionally stable.②The device was able to better simulate light, moderate and severe spinal cord blast injury in varying degrees. The present animal model of spinal cord blast injury is safe and effective and it is highly advantageous for the study of shockwave injury in laboratory.③The spinal cord blast injury may cause apoptosis of some neurons because the expressions of protective factor are less than the expression of the apoptosis factor.