血管性认知障碍小鼠模型皮质tau蛋白和胶质细胞病理学研究

Pathologies of cortical tau and glia cells in the mice with vascular cognitive impairment

目的:探讨血管性认知功能障碍模型小鼠皮质神经元丢失、tau蛋白病理及胶质化改变。方法:取22只ApoE-KO雄性4周龄小鼠,随机分为对照组(n=10)和模型组(n=12),模型组动物给予双侧颈动脉鞘管置入术。各组小鼠适应性喂养1周后,在手术前4周以高脂喂养,术后继续高脂喂养8周,采用水迷宫行为学实验评估两组小鼠空间学习和记忆能力,NeuN免疫组化染色计算皮质神经元数目,GFAP和IAB1免疫组化染色评估皮质星形胶质细胞和小胶质细胞增殖情况,嗜银染色分析皮质有无神经纤维缠结及淀粉样斑块形成,AT8染色检测皮质tau蛋白异常磷酸化表达。结果:在水迷宫试验中,模型组小鼠第3～5天潜伏期和游泳距离较对照组明显延长(P<0. 05)。模型组小鼠皮质神经元较对照组大量丢失(t=6. 181,P<0. 01),星形胶质细胞和小胶质细胞大量增生(t=7. 560,P<0. 01;t=3. 341,P<0. 01);与对照组对比,模型组皮质未发现明显神经纤维缠结和淀粉样斑块形成;模型组皮质AT8阳性神经元数目较对照组明显增多(t=10. 95,P<0. 001)。结论:高脂喂养并双侧颈动脉狭窄ApoE-KO小鼠存在认知功能障碍,病理学分析提示该认知功能障碍可能与皮质tau蛋白异常磷酸化、星形胶质细胞增生和小胶质细胞增殖有关。

Objective: To investigate the pathological changes of cortical neurons, tau protein and glia cells in mice with vascular cognitive dysfunction.Methods: Twenty-two ApoE-KO male 4-week-old mice were randomly divided into sham operation group(n=10) and model group(n=12). Animals in model group were given bilateral carotid sheath placement. After 1 week of adaptive feeding, mice in each group were fed with high fat for 4 weeks before operation and continued for 8 weeks after operation.The water maze behavioral experiment was used to evaluate the spatial learning and memory ability of animals in each group. NeuN staining was performed to detect the number of cortical neuron. GFAP and IAB1 staining were used to evaluate the proliferation of astrocytes and microglia cells in cortex of two groups. Silver staining was performed to determine the existence of neurofibrillary tangles and amyloid plaque in the cortex. AT8 staining was used to assess expression of cortical tau phosphorylation in each group.Results: In the water maze test, the latency and swimming distance during the 3th to 5th days of the model group were significantly longer than those of the sham operation group(P<0. 05). Prominent cortical neuron loss(t=6. 181, P<0. 01) and proliferation of astrocyte and microglia cells were found in the animals of the model group(t=7. 560, P<0. 01;t=3. 341, P<0. 01).Compared with that in the sham group, no obvious neurofibrillary tangles and amyloid plaque formation were observed in the cortex of model group. The number of cortical AT8 positive neurons in the model group was significantly higher than that of the sham operation group(t=10. 95, P<0. 001).Conclusion: High-fat feeding and bilateral carotid stenosis can trigger cognitive dysfunction in ApoEKO mice. Pathological analysis suggests that this cognitive dysfunction may be associated with abnormal phosphorylation of tau protein, proliferation of astrocytes and microglia cells.