大鼠脑微栓塞模型的建立

Establishment of microembolic model in rat brains

目的建立重复性好、稳定性高的大鼠脑微栓塞模型，为研究微栓子引起的神经细胞缺血性损害提供依据。方法54只SD大鼠随机分为假手术组（10只）和动脉粥样硬化斑块微栓塞模型组（44只），后者又按微栓子的大小分为106～150μm组（20只）、75～105μm组（12只）和55—74μm组（12只）。在手术显微镜下将静脉留置针外套管从颈外动脉逆行插管至颈内动脉，注入相应大小的动脉粥样硬化斑块微栓子，100个／只。24h后处死大鼠，采用HE染色、原位缺口末端标记（TUNEL）法及Caspase-3蛋白免疫组化染色观察神经细胞缺血性损伤程度。结果假手术组大鼠脑组织病理切片均未发现梗死灶。在106～150μm组、75～105μm组和55～74μm组中，大鼠脑梗死灶出现的比例分别为15／17、11／12和5／12；TUNEL阳性细胞数分别为（33．3±10．9）、（25．9±9．7）和（18．0±6．9）个／HP，明显高于假手术组的（5．7±2．7）个／HP（均P〈0．01）；Caspase-3阳性细胞数分别为（67±11）、（59±12）和（46±11）个／HP，明显高于假手术组的（7．8±3．1）个／HP（均P〈0．01）。结论55～150μm的动脉粥样硬化斑块微栓子能稳定地造成大鼠脑组织微梗死或神经细胞凋亡。

Objective To establish a well reproducible and highly stable microembolic model in rat brains and to provide a platform for investigating the ischemic neuronal injury of microemboli. Methods Fifty-four Sprague-Dawley rats were randomly assigned to sham-operation group （n = 10） and atherosclerot- ie plaque microembolic model group （n = 44 ）. The latter were further redivided into 106-150 μm （u = 20）, 75-105 μm （ n = 12） and 55-74 μm （ n = 12） groups according to the size of microemboli. Under the operating microscope, an indwelling venous catheter was inserted retrogradely from external carotid artery into internal carotid artery. Each rat was injected 100 corresponding microemboli of atherosclerotie plaque. The rats were killed after 24 hours. The severity of neuronal ischemic injury was detected by HE staining, the in situ TUNEL method for detection of apoptosis and immunohistochemistry staining for caspase-3 protein. Results No infarction was found in the pathological section of brain tissue in the sham-operation group. The proportion of cerebral infarction in the 106-150 μm, 75-105 μm and 55-74 μm groups were 15/17, 11/12 and 5/12, respectively, there was significant difference as compared with the sham-operation group （ P 〈 0.05 ） ; The numbers of TUNEL apoptosis were 33.3 ± 10.9, 25.9 ± 9. 7 and 18.0 ± 6. 9/ HP, respectively, and they were significantly higher than those in the sham-operation group （5.7 ± 2. 7/ HP） （all P 〈0. 01 ）. The cell numbers of positive expression of caspase-3 protein were 67 ± 11, 59 ± 12 and 46 ± 11/HP, respectively, and they were significantly higher than those in the sham-operation group （7.8 ± 3. 1/HP） （all P 〈 0.01 ）. Conclusion The microemboli of 55-150 tLm atherosclerotic plaque can stably result in microinfarction or neuronal apoptosis in rat brain tissues. This model may be used as an ideal means in the studying of physiopathology of cerebral microembolism.