不同位置脑损伤模型大鼠坐骨神经的再生

摘要

BACKGROUND:Previous studies have shown that traumatic brain injury can promote the regeneration of peripheral nerve by reducing scar collagen in nerve endings.OBJECTIVE:To investigate the effect of brain injury at different locations on the ipsilateral rat sciatic nerve regeneration.METHODS:Ninety-nine healthy male Sprague-Dawley rats were equivalently randomized into three groups:group A,right sciatic nerve transection;group B,right sciatic nerve transection combined with right brain injury;and group C,right sciatic nerve transection combined with left brain injury.All of transected nerves were sutured under microscope.Classical Feeney method was used to establish a model of traumatic brain injury.At 4,6,8,10 and 12 weeks after modeling,the sciatic functional index (SFI) was calculated by measuring footprint.At 4,8 and 12 weeks after modeling,the bilateral gastrocnemius were harvested for determining wet weight and calculate wet weight ratio,followed by acetylcholinesterase staining at the motor end plate to detect the absorbance values.At 4,8 and 12 weeks after modeling,fluoro-gold retrograde tracing was used to trace L4-5 vertebrae for 1 week,and the number of spinal cord anterior horn motor neurons positive for fluoro-gold was detected and calculated by fluorescence microscope.RESULTS AND CONCLUSION:The SFI value in each group was gradually improved with time.The SFI value was significantly higher in the groups B and C than the group A at 4 and 6 weeks after modeling (P ＜ 0.05),and was further improved in the group B at 8 weeks compared with the groups A and C (P ＜ 0.05).The wet weight ratio of gastrocnemius showed no significant difference among groups at 4 weeks after modeling (P ＞ 0.05),and the group B showed a significantly higher wet weight ratio than the other groups from the 8th week (P ＜ 0.05).Compared with the groups A and C,the absorbance values of motor endplate in group B appeared to be a significant increase at the beginning of the 8th week (P ＜ 0.05).At 4 and 6 weeks after modeling,the number of spinal cord anterior horn motor neurons positive for fluoro-gold was significantly nigher in the groups B and C than in the group A,and the number was significantly higher in the group B than the groups A and C at 12 weeks (all P ＜ 0.05).These finding manifest that brain injury can promote the repair of ipsilateral sciatic nerve injury,thus proving theoretical reference for unveiling the mechanism by which traumatic brain injury promotes peripheral nerve regeneration.%背景:课题组前期研究发现创伤性脑损伤可促进周围神经损伤的修复再生,这可能与减少神经断端胶原瘢痕形成有关.目的:观察不同位置脑损伤对大鼠同一侧坐骨神经损伤后修复的影响.方法:将99只SD雄性大鼠,按照完全随机分组原则,分为单纯右侧坐骨神经损伤组(A组)、右侧坐骨神经损伤并右侧脑损伤组(B组)、右侧坐骨神经损并左侧脑损伤组(C组).全部大鼠右侧坐骨神经完全切断,显微镜下吻合,B组同时采用Feeney方法建立右侧大脑皮质损伤模型,C组建立左侧大脑皮质损伤模型,于造模后4,6,8,10和12周各时间点踩足印并测量数值,计算坐骨神经功能指数;于造模后4,8和12周,取每组大鼠双侧腓肠肌,称湿质量并计算腓肠肌湿质量比;随后取右侧腓肠肌进行运动终板的乙酰胆碱酯酶染色,分析平均吸光度值;于造模后4,8和12周进行右侧坐骨神经处荧光金逆行示踪,示踪1周后取脊髓L4、L5节段做冰冻切片,荧光显微镜观察并计数被荧光金标记的脊髓前角运动神经元.结果与结论:①随时间延长,各组大鼠坐骨神经功能指数逐渐恢复,造模后4、6周时B和C组均优于A组(P＜0.05);自8周起,B组坐骨神经功能指数恢复明显优于A组与C组(P＜0.05);②在造模后4周,3组大鼠的腓肠肌湿质量比无明显差异(P＞0.05);自8周起,B组明显高于A和C组(P＜0.05);③腓肠肌运动终板乙酰胆碱酯酶染色后,在造模后4周,3组间腓肠肌运动终板吸光度差异无显著性意义.自8周起B组吸光度值明显高于A和C组(P＜0.05);④在造模后4周时,B组与C组的荧光金阳性脊髓前角运动神经元的数目均明显多于A组(P＜ 0.05);12周时B组荧光金阳性神经元数量明显较A和C组多(P＜0.05);⑤结果提示,伴有同侧脑损伤可促进大鼠坐骨神经损伤修复再生,这为进一步揭示创伤性脑损伤可促进周围神经损伤的具体机制提供理论依据.