过表达血管内皮生长因子对颅脑损伤大鼠神经保护作用及其作用机制

Neuroprotective effect and mechanism of overexpression of vascular endothelial growth factor on brain injury in rats

目的探讨过表达血管内皮生长因子(VEGF)对颅脑损伤大鼠神经保护作用及作用机制。方法 60只SD大鼠按照随机数字表法分为对照组、脑损伤组和VEGF组。脑损伤组和VEGF组大鼠建立颅脑损伤模型,对照组仅分离皮肤,不进行颅脑损伤。VEGF组大鼠经颅内注射过表达VEGF的腺相关病毒1×1010 vg/只,对照组和脑损伤组大鼠经颅内注射对照腺相关病毒1×1010 vg/只;3组治疗4周后,采用神经行为学评分分析大鼠神经功能;采用酶联免疫吸附试验(ELISA)分析脑组织炎性因子的水平;采用末端脱氧核苷酸转移酶介导的dUTP缺口末端标记(TUNEL)染色观察大鼠脑组织凋亡水平;采用免疫荧光染色分析脑组织神经元细胞数量。计量数据比较采用方差分析。结果 VEGF组大鼠改良神经功能评分(mNSS)评分[(7.29±2.98)分]明显低于脑损伤组[(12.54±3.90)分],差异有统计学意义(t=4.819,P<0.05)。VEGF组大鼠逃避潜伏期[(28.18±5.44)s]明显高于脑损伤组[(43.59±7.30)s],差异有统计学意义(t=6.115,P<0.05)。VEGF组大鼠穿台次数[(50.14±6.32)s]明显高于脑损伤组[(38.74±8.19)次],差异有统计学意义(t=4.905,P<0.05)。VEGF组大鼠脑组织神经元细胞数量[(43.89±7.18)个/视野]明显高于脑损伤组[(31.44±6.39)个/视野],差异有统计学意义(t=4.103,P<0.05)。VEGF组大鼠外周血肿瘤坏死因子-α(TNF-α)、白细胞介素(IL)-6和IL-1β炎性因子水平[(103.48±8.18)、(167.39±9.28)、(114.52±9.87) pg/ml]明显低于脑损伤组[(187.38±12.47)、(215.31±14.21)、(165.83±13.09) pg/ml],差异均有统计学意义(t=3.198、3.004、2.896,P<0.05)。VEGF组大鼠脑组织TUNEL阳性率[(15.33±4.28)%]明显低于脑损伤组[(29.41±5.39)%],差异有统计学意义(t=3.174,P<0.05)。结论过表达VEGF可显著降低炎性因子水平和神经细胞凋亡,进而保护颅脑损伤大鼠神经功能和学习记忆能力。

Objective To investigate the neuroprotective effect and mechanism of overexpression of vascular endothelial growth factor(VEGF)on brain injury in rats.Methods A total of 60 SD rats were randomly divided into control group,brain injury group and VEGF group(n=20 in each group).The model of brain injury was established in the brain injury group and VEGF group.In the control group,only the skin was separated without brain injury.The rats in VEGF group were injected with adeno-associated virus which overexpressed VEGF.The rats in control group and brain injury group were injected with control adeno-associated virus 1×1010 vg/mouse.After 4 weeks of treatment,neurobehavioral score was used to analyze the neurological function.The levels of inflammatory factors in brain tissue were analyzed by enzyme linked immunosorbent assay(ELISA).The level of apoptosis was analyzed by TdT mediated dUTP Nick End Labeling(TUNEL)staining.The number of neurons in brain tissue was analyzed by immunofluorescence staining.The measurement data were compared by ANOVA.Results The modified neurological severity scores(mNSS)in VEGF group(7.29±2.98)were significantly lower than those in brain injury group(12.54±3.90)(t=4.819,P<0.05).The escape latency in VEGF Group[(28.18±5.44)s]was significantly longer than that in brain injury group[(43.59±7.30)s,t=6.115,P<0.05].The cumulative immobility time in VEGF group[(50.141±32)s]was significantly greater than that in brain injury group[(38.746±8.19)(t=4.905,P<0.05).The number of neurons in VEGF group[(43.89±7.18)cells/field]was significantly greater than that in brain injury group[(31.44±6.39)cells/field,t=4.103,P<0.05].Tumor necrosis factor-α(TNF-α),interleukin(IL)-6 and IL-1 levels of peripheral blood in VEGF group[(103.48±8.18),(167.39±9.28),(114.52±9.87)pg/ml]were significantly lower than those in brain injury group[(187.38±12.47),(215.31±14.21),(165.83±13.09)pg/ml,t=3.198,3.004,2.896,P<0.05].The positive rate of TUNEL in VEGF group[(15.33±4.28)%]was significantly lower than that in brain injury group[(29.41±5.39)%,t=3.174,P<0.05].Conclusion Overexpression of VEGF can significantly reduce the levels of inflammatory factors and neuronal apoptosis,thereby protecting the neural function and learning and memory ability of rats with traumatic brain injury.