转化生长因子-β1对脊髓损伤后神经细胞凋亡的影响

The effects of TGF-β1 on the apoptosis of nerve cells after spinal cord injury in rats

目的探讨转化生长因子（Transforming growth factor-β1，TGF-β1）对大鼠脊髓损伤后神经细胞凋亡及神经动能恢复的影响。方法采用改良Allen’s撞击法制作脊髓损伤大鼠模型，根据干预方式不同随机分为对照组、模型组、TGF—β1治疗组（渗透微泵持续蛛网膜下腔泵入1μg／hTGF—β1）、TGF-β1抗体组（渗透微泵持续蛛网膜下腔泵入1μg／h TGF—β1中和抗体），按设定的不同时间点随机处死各组的实验动物，取材。应用TUNEL法、RT—PCR、Western blot和免疫组织化学染色分别检测不同组别在神经细胞凋亡，脊髓组织细胞中TGF—β1和Fas的mRNA及蛋白质表达差异。通过BBB运动功能评分法评估大鼠后肢运动功能恢复情况。结果脊髓损伤后TGF—β1和Fas表达时间依赖性增加，Fas表达24h达高峰，TGF—β1表达7d达高峰。脊髓损伤后神经细胞凋亡增加，其中8h神经元凋亡明显，7d神经胶质细胞凋亡明显。局部应用TGF-β1，可显著下调损伤脊髓组织Fas表达，减少8h和7d时神经元凋亡及神经胶质细胞凋亡数量，BBB运动功能评分结果显示，TGF—β1治疗组大鼠后肢运动功能明显改善（P〈0．01）。结论脊髓损伤部位应用TGF-β1可抑制FasmRNA及蛋白质的表达，减少脊髓损伤部位神经细胞的凋亡，有利于促进脊髓神经功能的恢复。

Objective To investigate the effects of exogenous transforming growth factor β1 on the apoptosis of nerve cells and its functions following spinal cord injury in rats. Methods Ninety-six male Wistar rats were randomly divided into 4 groups： group A （control group）, group B （spinal cord injured group）, group C （spinal cord injuried ＋TGF-β1 treated group）, group D （spinal cord injuried ＋anti-TGF-β1 treated group）. The rat model of spinal cord injury was found by the Allen＇s method. In group C and D, drugs were injected into subarachnoid cavity continuously by minipump. The changes of spinal cord were observed by HE staining. Nerve cells apoptosis was detected by transferase-medi-ated dUTP nick end labeling （TNUEL） method and the expression of cell apoptosis factor Fas by immunohistochemistry staining. Functional recovery of hind limbs was measured by Basso-Beattie-Bresnahan locomotor open field behavioral rating test. Results The expression of TGF-β1 and Fas increased following spinal cord injury. The amount of TGF-β1 and Fas reached the peak 7days and lday after injury. The apoptosis of neuron had increased and peaked 8 hours after injury. The apoptosis of neuroglia cells had increased and peaked 7 dayss after injury. The slight changes was found in spinal cord in group C. Both of the number of apoptosis of nerve cells and expression of the apoptosis factor （Fas） decreased significantly; compare with group B and D. The BBB score was higher in group C than that in group B and D. Conclusion TGF-β1 can improve the functional recovery of spinal cord by inhibiting the nerve cell apoptosis after the spinal cord injury.