Correlation between caspase regulatory gene expression and facial nerve injury in a facial nerve injury model

doi:10.3969/j.issn.2095-4344.2014.27.016

Abstract

Abstract:

BACKGROUND: Caspase plays a crucial role in the cell apoptosis, but the influence of different facial nerve injury on caspase 1, caspase 8, cyto-c protein expression and their correlation still remain unclear.
OBJECTIVE: To construct facial nerve crush or distal transection injury models, observe the morphological changes of facial motoneurons, investigate death gene caspase 3, caspase 8, cyto-c expression, and analyze their correlation.
METHODS: Facial nerve crush or distal transection injury model was established in the right facial nerve of rats, while the left facial nerve served as normal controls. We observed the morphology and the death of facial motoneurons with toluidine blue staining and transmission electron microscope. Expressions of caspase 3, caspase 8 and cyto-c proteins were studied by immunohistochemistry analysis following facial nerve injury.
RESULTS AND CONCLUSION: Both facial nerve distal transection and crush injury resulted in the death of
facial motoneurons, and the death pattern was mainly apoptosis. Caspase 3, caspase 8 and cyto-c protein expressions were observed in the subnucleus of normal rat facial nucleus. Cells of the distal transection group were stained more intensely than that of crush group. Expressions of these proteins began to increase at 3 days after the injuries. Caspase 3 and caspase 8 protein expression peaked at 14 days, whereas cyto-c protein expression peaked at 7 days after the injuries. Expressions of caspase 3, caspase 8 and cyto-c proteins were correlated with facial nerve injury type and injury time. Expressions of caspase 8 and cyto-c protein were correlated with expression of caspase 3 protein. The findings indicate that, caspase 8 and cyto-c contribute to activate caspase 3, and caspase cascade reaction plays an important role in the apoptosis of facial motoneurons.

中国组织工程研究杂志出版内容重点：肾移植；肝移植；移植；心脏移植；组织移植；皮肤移植；皮瓣移植；血管移植；器官移植；组织工程

全文链接：

Key words: facial nerve, cell death, caspases, gene

CLC Number:

R318

Wei Hai-gang, Li Shu-guang, Chen Yu-ting, Cai Chao-xiong, Xu Biao. Correlation between caspase regulatory gene expression and facial nerve injury in a facial nerve injury model[J]. Chinese Journal of Tissue Engineering Research, 2014, 18(27): 4362-4367.

Figures/Tables 3

2.1 实验动物数量分析实验选用大鼠98只，实验过程无脱失，全部进入结果分析。 2.2 各组大鼠造模后大体观察结果损伤后1周时，所有动物进食、活动正常，损伤侧触须集中伸直并向后伸展，完全不能抖动，呈现完全性面瘫。损伤后2周时，压榨伤组大鼠损伤侧触须在完全性面瘫基础上，触须能部分抖动。切断伤组动物的触须仍完全不能抖动。损伤后4及6周时，压榨伤组大鼠的面瘫症状基本完全恢复，触须回到正常位置，抖动基本与左侧一致。切断伤组动物损伤侧触须仅出现轻微抖动。 2.3 各组大鼠面运动神经元光镜观察结果面神经低位断裂伤及压榨伤均可引起面运动神经元死亡，损伤后28 d时达到死亡高峰，死亡率分别为51%和28%。低位断裂伤组面运动神经元死亡率明显高于压榨伤组。 2.4 各组大鼠面运动神经元透射电镜观察结果正常面神经核团中面运动神经元胞体中央有大而圆的细胞核，常染色质丰富，絮状分布，核异染色质少，着色浅，细胞器正常。面神经损伤后，无论是断裂伤组或是压榨伤组，均可见到运动神经元胞体缩小呈固缩状态，胞核皱缩，DNA浓缩、核不规则变形，保存的细胞器胞质浓缩和典型凋亡细胞的膜出泡现象，细胞器正常，也符合凋亡细胞特征，而不象坏死细胞首先表现为细胞体破坏，胞膜破裂，胞浆外溢，溶酶体释放，引起周围组织炎症反应。断裂伤组面运动神经元细胞损伤程度较压榨伤组严重[1]。 2.5 各组大鼠面运动神经元死亡相关基因caspase 3、caspase 8、cyto-c的表达：免疫组织化学及图像分析结果光镜下caspase 3，caspase 8和cyto-c蛋白表达均定位于细胞胞浆，偶有胞核着色，呈色为棕褐色。除神经元细胞外，胶质细胞也有着色。损伤后不同时期各蛋白表达(图1)。 2.6 大鼠面神经损伤后面神经核团阳性单位值(Pu)右左侧比值(R/L)的动态观察切片经图像分析仪分析处理，计算出右左侧阳性单位值(Pu)之比(R/L)，其表达变化(表1)。"

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