经鼻给神经生长因子对大鼠脑外伤后β-淀粉样蛋白表达的影响

Effect of nerve growth factor delivering intranasally on β-amyloid deposition after traumatic brain injury in rats

目的探讨经鼻给神经生长因子（NGF）对实验性创伤性脑损伤（TBI）大鼠中枢神经系统中β-淀粉样蛋白（Aβ）表达的影响。方法将80只大鼠采用完全随机分组法分为假手术组（n=26）、对照组（n=27）和治疗组（n=27），参照Feeney自由落体法制作TBI大鼠模型，治疗组经鼻给予NGF治疗。采用平衡木和Morris水迷宫方法评估3组大鼠的神经功能恢复情况。取伤侧海马，通过ELISA方法定量各组大鼠海马部位AB的表达；行免疫组织化学染色检测各组大鼠脑组织中淀粉样蛋白前体（APP）的生成情况。结果治疗组TBI大鼠与对照组相比，平衡木运动协调功能（s）恢复较快（19．00±6．99与27．33±7．39，F2，5=12．87，P=0．028），Morris水迷宫实验显示治疗组潜伏期明显短于对照组；治疗组在原平台象限所占时间百分比（45．82±11．15％）及穿越平台次数（8．60±2．73）较对照组（33．99％±3．46％、3．60±2．06）均明显增多（F2）5=6．814，P=0．037；F2 15=5．346，P=0．04）。ELISA检测显示治疗组A13浓度的增高幅度较对照组下降显著。免疫组织化学观察发现APP的阳性细胞数目在3组之间差异有统计学意义（F2，5=8．672，P=0．003），但对照组和治疗组相比差异无统计学意义。结论经鼻给NGF可降低TBI大鼠中枢神经系统中Aβ的表达，促进损伤后神经功能的恢复。

Objective To study the effect of intranasal nerve growth factor （NGF） on the expression of amyloid-β peptide （Aβ） in the central nervous system in rats with traumatic brain injury （TBI）. Methods Eighty rats were randomly divided into sham （ n = 26 ）, control （ n = 27 ） and treatment group（ n = 27）. They were subjected to the modified Feeney＇ s weight-drop model. The treatment group was treated with NGF administered by nasal route, and the control group was given phosphate-buffered saline （PBS）. Beam walking and Morris water maze test were performed in the three groups. The concentration of Aβ40 and Aβ42 in the injured ipsilateral hippoeampus was elevated by ELISA measurement. Immunohistochemistry was used to detect the amyloid precursor protein （APP） positive cells near the region of injury in the hippocampus in rats after TBI. Results NGF group traversed the beam significantly quicker （s） than control group （ 19. 00 ± 6. 99 vs 27. 33 ± 7.39 respectively, F2,15 = 12. 87, P = 0. 028 ）. Morris water maze performance revealed that mean time of latency in the NGF group was significant shorter than vehicle group, and significant memory retention in NGF group as evidenced by a greater percentage of the 60 s allotted time spent in the target quadrant （45.82% ± 11.15% vs 33.99% ± 3.46% , F2,15 = 6. 814, P = 0. 037） , as well as the number crossing of the former site of the removed platform in NGF group was significant more than control group （8. 60 -±2. 73 vs 3.60 -±2. 06, F2,15 =5. 346,P =0. 04）. The Aβ42 level in control group was increased significantly higher than NGF group as indicated by ELISA measurements. While the A1340 level did not have similar shown. Immunohistochemical staining showed that APP level had significant differences among three groups （F2,15 = 8. 672 ,P =0. 003）. The APP level in NGF group did notalter with control group. Conclusion Intranasal administration of NGF can regulate Aβ42 overproduction, improve the motor and cognitive function after brain injury in rats.