星形胶质细胞的形态变化与损伤时间的关系

Relationship between astrocytic heterogeneity and wound age after traumatic brain injury in mice

目的通过检测小鼠脑挫伤后不同时间点星形胶质细胞的树突数目、长度、复杂程度等形态学特征,探索星形胶质细胞形态与损伤时间的相关性。方法采用PCI3000颅脑打击器制作小鼠可控皮质打击模型,应用免疫荧光染色法标记星形胶质细胞,并应用Sholl分析测量伤后1d、3d、7d、14d、21d、28d不同时间点星形胶质细胞形态的变化。结果免疫荧光染色显示,假手术(sham)组皮质未见GFAP阳性细胞。脑挫伤后3d损伤周边区观察到阳性细胞,伤后7d数量到达峰值,随后降低,其中A1亚型星形胶质细胞损伤后3d开始出现,损伤后7d占比最高。损伤后,树突数目3d最多,之后逐渐减少,树突长度3d最短,之后逐渐增加。Sholl分析结果显示,距离胞体20μm~40μm范围内细胞复杂程度在伤后逐渐加大,7d到达高峰,之后降低。结论小鼠脑皮质损伤后星形胶质细胞内GFAP呈动态表达,星形胶质细胞的树突数目、树突长度、树突复杂程度等形态学指标与损伤经过时间存在相关性,提示星形胶质细胞的形态变化有望成为推断脑挫伤时间的辅助指标。

Objective To investigate the morphology(dendrites number,length and complexity)of astrocytes at different time points after traumatic brain injury and its relationship with wound age of mice.Methods Using PCI3000,a mouse brain contusion model was established.Morphology of astrocytes and expression of GFAP were detected with immunofluorescence at different time points.Sholl analysis was used to assess the complexity of astrocyte.Results Immunofluorescent staining results showed no GFAP+cell in the cerebral cortex of sham group.GFAP showed strongly positive expression 3 days after injury,most prominent at 7 days.The proportion of A1 astrocytes reached the peak on day 7.The length of astrocyte processes was increased by time.While the number of astrocyte processes was decreased with post-injuried time extension.Sholl analysis showed the complexity within 20-40μm from the cell soma grew from 3 days after TBI,then decreased at 7 days.Conclusion GFAP expression increased after brain contusion.The changes of astrocytes morphology are time-dependent,which suggests its potential applicability as a biological indicator for wound age estimation of brain contusion in forensic practice.