四氯化碳对大鼠海马CA1区神经元低亲和力神经生长因子受体p75表达的影响

THE INFLUENCE OF CARBON TETRACHLORIDE UPON THE EXPRESSION OF LOW-AFFINITY NEURAL GROWTH FACTOR RECEPTOR-p75 IN HIPOCAMPAL CA1 AREA NEURONS

目的研究四氯化碳(CCl4)对大鼠脑海马CA1区神经元低亲和力神经生长因子受体p75的表达和凋亡的影响。方法将24只健康雄性Wistar大鼠随机分为对照组和CCl4组。对照组每周一、四背部皮下注射橄榄油(0.12ml/100g),CCl4组分别在每周一或/和周四背部皮下注射60%CCl4-橄榄油溶液(0.3ml/100g)1次(1d组)2、次(1周组)和4次(2周组),实验结束时处死大鼠。取脑后沿正中矢状面切开,右侧半脑石蜡切片,行Nissl染色,观察海马CA1区神经元的形态学改变;行p75、Bax免疫组织化学染色和Western blotting分析,检测海马CA1区神经元p75、Bax的表达,行原位缺口末端标记法(TUNEL)观察海马CA1区神经元的凋亡。结果Nissl染色显示对照组CA1区神经元染色较深,细胞数目较多,排列整齐,神经元内可见大量尼氏体;CCl4组CA1区神经元排列较对照组紊乱,部分锥体细胞体积缩小,核固缩,呈三角形,胞浆内尼氏体数目减少或消失。对照组海马CA1区可见少量表达p75和Bax的阳性细胞;CCl4组海马CA1区表达p75和Bax的阳性细胞数较对照组明显增多,以1周CCl4组增多最为明显;Western blotting结果与免疫组织化学染色结果一致。对照组海马CA1区未见TUNEL阳性细胞;CCl4组海马CA1区可见大量细胞核呈棕黄色着色的TUNEL阳性细胞,以1周CCl4组的阳性细胞数最多。结论注射CCl4后,大鼠脑海马CA1区p75的表达明显增强,Bax的表达也相应增强,凋亡的神经元明显增多。

Objective This study aimed to research the influence of CCl4 on the expression of p75 and apoptosis in hippocampal CA1 area neurons. Methods Healthy adult male Wistar rats were randomly divided into control group and CCl4 groups. The control group was subcutaneously injected olive oil solution with 0.12ml/100g rat weight on every Monday or/and Thursday, the CCl4 groups were subcutaneously injected 60% carbon tetrachloride olive oily solution with 0.3ml/100g rat weight on every Monday or/and Thursday for one time（one day group）, two times（one week group）, four times（two-week group） respectively. When the experiment ended, all the rats were killed. Brains were taken out and separately slivered into two parts along median sagittal plane. The right parts were embedded in paraffin wax and sliced, the morphological changes of hippocampal CA1 area neurons were observed by Nissl staining. The expressions of p75 and Bax in hippocampal CA1 area neurons were detected by immunohistochemical staining and Western blotting analysis. The apoptosis of hippocampal CA1 area neurons was observed by TUNEL staining. Results The color of Nissl staining was deeper, the number was more and the structure was more regular than that of the CCl4 groups, and there were more Nissl＇s bodies in the control group; while in the CCl4 groups, the staining was lighter and the structure was less regular than that of the control group, some pyramidal cells shrunk, their nuclear dwindled and presented triangles, and there were less or no Nissl＇s bodies. There were a few p75 and Bax positive cells in the control group, but p75 and Bax positive cells increased obviously in every CCl4 group; and increased most obviously after injecting CCl4 for two times. In Western blotting, the expression of p75 and Bax was the same as the results of immunohistochemical staining. There was no TUNEL positive cell in the control group, but more brown nucleus-stained TUNEL positive cells could be observed in the CCl4 groups, and the one week CCl4 group presented the most TUNEL positive cells. Conclusion After the injection of carbon tetrachloride, the expression of p75 increased evidently in hippocampal CA1 area neurons, the expression of Bax enhanced correspondently, apoptotic neurons also increased markedly.