不同脑温对树鼩局部脑缺血海马血管内皮细胞生长因子表达的影响

The Effect of Different Brain-temperature on VEGF Expression in Tree Shrew Hippocampus Following Photochemistry Induced Thrombotic Cerebral Ischemia

目的研究不同脑温(亚低温、常温及高温)对树鼩局部脑缺血海马CA1区内皮细胞生长因子(vascular endothelial growth factor,VEGF)表达的影响,探讨缺血时脑温对VEGF表达的影响。方法建立光化学诱导树鼩皮层脑缺血模型,于缺血后6h采用局部恒温控温装置维持脑温在亚低温(31～32℃)、常温(36～37℃)和高温(39～40℃)三种不同温度状态持续1h。于缺血后24h及72h处死动物,用免疫组化染色方法染色及图像分析仪测定海马CA1区VEGF表达的不同强度。结果局部脑缺血后海马CA1区VEGF表达随温度的增加而减弱,亦随时间的延长而减弱;其中以72h时31℃组VEGF的表达下降最为明显(P<0.01)。结论亚低温后处理将在脑缺血的早期发挥脑保护作用,其脑保护作用可能与亚低温能增强VEGF的表达有关。低温脑保护的意义在于延长脑缺血治疗时间窗。

Objective To observe the changes of vascular endothelial growth factor（VEGF） expression at （tifferent temperature（subhypothermia, normal temperature and hyperthermia） after cerebral thrombosis in hippocampus CAI area of tree shrew. Discuss the VEGF expression at different brain-temperature after cerebral thrombosis. Methods The focal thrombotic cerebral ischemia was induced by photochemical reaction in tree shrews. Different temperature was initiated 6 hours after ischemia, temperature varied from subhypothermia （ 31 ℃ - 32 ℃ ）, normal temperature（ 36 ℃ - 37 ℃ ） and hypenhermia（ 39 ℃- 40℃ ）, duration 1 hour by focal homeothermia equipment. The absorbance of VEGF expression in neuron of hippocampus CA1 area was detected by immunohistochemistry in 24h, 72h after focal cerebral ischemia, using high definition image analysis. Results VEGF expressions increased in neuron of hippocampus CAI area in subhypothermia group and reduced in hyperthermia group, especially in 31℃ group, they decreased obviously at 72h. Conclusion Hypothermia is remarkably neuroprotective at the acute phase of cerebral ischemia, this neuron protection may be related to increase of expression of VEGF by hypothermia. The hypothermia - induced neuroproteetion provided longer treatment time-windows in the acute phase of cerebral isehemia.