脊髓损伤后Bcl-2抗神经元凋亡的研究

目的 通过研究Bcl-2(B-cell lymphoma/Leukemia-2)高表达转基因小鼠的脊髓损伤模型,探寻Bcl-2抗神经元凋亡,减轻脊髓继发性损害的作用.方法 将Bcl-2质粒转入小鼠的受精卵,培育Bcl-2转基因小鼠.转基因(A组)及同窝非转基因小鼠(B组)各9只随机(随机数字法)分为三组(1d,7 d,14 d),采用垂直打击脊髓(weight dropping,WD)方法,以2.5×3.0 g·cm致伤力致伤小鼠脊髓.另取3只非转基因小鼠设为假手术组(C组),仅打开椎板,暴露脊髓,不做打击.于术后1 d,7 d,14 d分别行:①小鼠后肢运动功能(BBB)评分;②HE染色观察;③原位末端标记法(TUNEL)染色.结果 打击后所有小鼠均出现双侧的后肢瘫痪,两周内BBB评分,A组(5.45±0.15)和B组(5.05±0.35),差异无统计学意义,P=0.67;HE染色提示A组小鼠的脊髓损伤程度较B组鼠要轻;原位末端标记法(TUNEL)染色表明A组小鼠TUNEL阳性的神经元(3.67±2.08/HP)明显小于B组小鼠(12±4/HP),P=0.033;积分光密度(Integration Optic Density,IOD)值(458.33±112.7)A组也明显小于B组小鼠(2436.33±228.01),P=0.000,其差异均具有统计学意义;C组未见明显的TUNEL阳性神经元.结论 Bcl-2蛋白是中枢神经系统内在的,重要的抗损伤因子,过表达Bcl-2能够抑制损伤后神经元的凋亡,从而减轻脊髓的损伤.

Study on the role of Bcl-2 in anti- neuronal apoptosis after spinal cord injury

Objective To study the variables of behavioral function and TUNEL (terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling) figure in Bcl-2 transgenic (TG) mice and control mice after spinal cord injury (SCI), thus to find new ideas and ways for diagnosing and treating SCI. Method The genesis of Bcl-2 overexpression transgenic (TG) mice were produced by injection of Bcl-2 plasmid into the fertilized ova of mice.Nine Bcl-2 TG mice and nine control mice were subjected to SCI of moderate severity at T10, with the use of weight dropping (WD) method (impact force 2.5～3.0 g·cm). Up to 1 day , 7 days, and 14 days after SCI,functional deficits were evaluated with BBB scales, and the apoptosis of neurons was investigated by using TUNEL method. Another three mice of control group were only treated with laminectomy without SCI for comparison. Results The mean functional scores in the control mice were lower than those in the Bcl-2 TG mice, although the unpaired T -test revealed no significant differences. On the other hand, the number of TUNEL positive neurons and IOD(Integrated Optical Density)score in the Bcl-2 TG mice were both significantly lower than those in the control mice. Conclusions This experiment suggests that overexpression of Bcl-2 may suppress neuronal apoptosis after SCI. The Bcl-2 may be an important factor in relieving the damage within CNS after trauma.