大鼠脑损伤后GDNF表达变化的时间规律性研究

目的探讨大鼠脑损伤后胶质源性神经营养因子(GDNF)在神经元、神经胶质细胞中表达变化的时间规律性。方法以冲击应力σd为355.09kPa致大鼠脑损伤后,于不同时问段分别应用原位杂交、免疫组化、免疫组化双染色技术检测GDNF mRNA和蛋白的表达强度,用图像分析系统测定阳性反应物平均灰度,进行统计学分析。结果正常对照组GDNF mRNA和蛋白弱表达,伤后15min开始表达呈增强趋势,分别于伤后1d、2d,表达至峰值,平均灰度值分别为133.08±4.53、125.05±2.00,与对照组、邻近上组比较均具有显著性差异(P<0.05),并维持高水平表达至伤后7d,平均灰度值分别为116.65±1.31、114.20±1.68,与对照组比较具有显著性差异(P<0.05)。表达至峰值前,阳性细胞多为神经元,之后以神经胶质细胞为主。结论脑损伤后GDNF mRNA及蛋白的表达具有时间规律性,GDNF阳性细胞种类存在变化,可作为法医学推断脑损伤形成时间的指标。

The dynamical changes of GDNF and the gene expression of GDNF mRNA after traumatic brain injury in rats

Objective To investigate the pathology of TBI and to understand the relationship between the expression of GDNF and the timing of traumatic brain injury ( TBI). Methods Immunohistochemical staining, double-labeled with the anti-GDNF antibody and with either the neuron-specific antibody NeuN or the astrogli-al-specific marker GFAP, and in situ hybridization were performed and computer image analysis were used. Results GDNF mRNA and GDNF were faintly expressed in mostly neurons at the cerebral cortex of control group, the staining intensity was increased 15 min post-injury, and peaked at Id and 2d after injury, respectively. Significant differences in GDNF protein were present between control and 2d post-injury (P < 0. 05). The intensely stained cells persisted in a high level after 2 days, and significant differences (P < 0. 05 ) even presented between control and 7d post-injury. The GDNF mRNA was expressed faintly in the cerebral cortex in the control group, expressed increasingly since 1h after TBI and reached the maximum (P < 0. 05) at 1d post-injury with a high level till 7d post-injury (P <0. 05). Conclusion The results indicated that the expression of GDNF mRNA and GDNF protein had a possible relationship with the extending time after TBI. The cells expressing GDNF were mostly neurons before 1 d post-injury, with astroglias after 2d post-injury.