采用改良术式建立大鼠颅内动脉瘤模型

Establishment of a rat model of intracranial aneurysm with modified procedure

目的探讨采用改良术式对大鼠颅内动脉瘤模型建立的影响。方法取SD大鼠55只,随机分为3组。传统方法组20只,结扎左侧颈总动脉+切断两侧肾动脉后支(各1支)。改良术式组20只,结扎并切断左侧颈总动脉+电凝并切断两侧肾动脉(每侧各2支或肾动脉分支中粗的1支)。阴性对照组15只,未采取任何干预措施。术后当天开始投喂等渗盐水+质量分数为0.12%的β-氨基丙腈饲料。4周后处死大鼠。在显微镜下脑底部分离脑动脉,取双侧大脑前动脉和嗅动脉(ACA/OA)的分叉处或动脉瘤发生处的脑动脉,在光镜下观察其病理变化。在术前、术后第3周处死大鼠的当天,通过尾套测压法测量收缩压。结果传统方法组大鼠ACA/OA分叉处均未见有进展期动脉瘤。改良术式组6只大鼠死于动脉瘤性蛛网膜下腔出血,在其余14只中,发现10个进展期动脉瘤;处死前,3组大鼠的血压平均值分别为(164.3±3.0)、(195.3±1.9)和(116.2±2.6)mmHg。传统方法组中发现2只有早期动脉瘤样改变,表现为内弹性层不连续,但无明显动脉壁膨出。改良术式组中16个动脉瘤均为进展期动脉瘤,在高倍光镜下,均可见内弹性层断裂、肌层变薄及动脉壁膨出;还发现3只大鼠有早期动脉瘤性改变。阴性对照组未发现动脉瘤。结论改良术式不仅可缩短动脉瘤形成时间,而且可提高动脉瘤形成率,这可能与短时间内血压升高有关。

Objective To evaluate the effect of a modified procedure on the establishment of a model of cerebral aneurysm in rats. Methods Fifty-five SD rats were randomized into three groups： traditional method （ group A, n = 20） , modified procedure （ group B, n = 20 ） , and control （ group C, n = 15 ）. Left common carotid artery and one posterior branch of bilateral renal arteries were ligated in the group A; left carotid artery was ligated and cut off, and bilateral renal arteries were electrocoagulated and cut off （two branches on each side or the one dominant branch of bilateral renal arteries） in the group B; and no intervention was performed in the group C. The rats were fed isosmotic saline and 0. 12% betaaminopropionitrile （BAPN） on the same day after procedure, and were sacrificed four weeks after the procedures. Cerebral arteries were isolated from basal parts of the brain under a microscope. Anterior cerebral artery/olfactory artery （ACA/OA） bifurcations or a part of artery near the aneurysm were taken out, and their pathological changes were observed under light microscope. Systolic blood pressure was measured by the tail-cuff method before the procedures, 3 weeks after the procedures, and on the same day the rats were sacrificed. Results Advanced aneurysm was not found on the ACA/OA bifurcations in group A. Six rats died of aneurysmal subarachnoid hemorrhage in group B, and 10 advanced aneurysms were found in the remaining 14 rats. Mean systolic blood pressure were （ 164. 3 ± 3.0 ） mm Hg, （ 195.2 ± 1.9 ）mm Hg, and （116. 2 ±2. 6） mmHg respectively before the rats were killed in the three groups. Early aneurysmal change in two rats was found in group A, the change consisted of discontinuity of the internal elastic lamina, but no apparent outward bulging of the arterial wall. Sixteen saccular aneurysms were all advanced aneurysms in group B, the breaks in internal elastic lamina, muscular layer becoming thinner and outward bulging of the arterial wall could be visualized under the light microscope ; and early aneurysmal change was also found. No aneurysm was detected in group C. Conclusion The modified procedure can not only shortens the time of aneurysm formation, but also increases the rate of aneurysm formation, which may be associated with the elevation of blood pressure in a short period of time.