小鼠脑挫伤后CB2R的表达变化与损伤时间的关系

Relationship between Expression Changes of CB2R and Wound Age of Brain Contusion in Mice

目的检测小鼠脑挫伤后不同时间点大麻素2型受体(cannabinoid type 2 receptor,CB2R)的表达情况,并探索其与损伤时间的相关性。方法通过PCI3000精密颅脑损伤撞击器建立小鼠脑挫伤模型,利用免疫组织化学染色、免疫荧光染色和Western印迹法检测不同损伤时间点损伤区周围CB2R的表达变化。结果免疫组织化学染色结果显示,假手术组脑皮质中仅少量细胞呈CB2R阳性表达,脑挫伤后CB2R阳性细胞率逐渐升高,于伤后12h和伤后7d两次达到高峰,随后逐渐下降,至伤后28d基本恢复至正常水平。Western印迹法检测结果与免疫组织化学染色结果一致。免疫荧光染色结果显示,脑挫伤后CB2R阳性神经元、CB2R阳性单核细胞、CB2R阳性星形胶质细胞数与总细胞数的比值变化均呈单峰模式,分别于伤后12h、1d、7d达到高峰。结论小鼠脑挫伤后CB2R在神经元、单核细胞及星形胶质细胞中的表达提示,其可能参与调节这些细胞的生物学功能。脑挫伤后CB2R的动态表达存在时间规律性,有望成为法医学脑挫伤损伤时间推断的生物学指标。

Objective To investigate the expression of cannabinoid type 2 receptor (CB2R) at different time points after brain contusion and its relationship with wound age of mice. Methods A mouse brain contusion model was established with PCI3000 Precision Cortical Impactor. Expression changes of CB2R around the injured area were detected with immunohistochemical staining, immunofluorescent staining and Western blotting at different time points. Results Immunohistochemical staining results showed that only a few cells in the cerebral cortex of the sham operated group had CB2R positive expression. The ratio of CB2R positive cells gradually increased after injury and reached the peak twice at 12 h and 7 d post-injury, followed by a decrease to the normal level 28 d post-injury. The results of Western blotting were consistent with the immunohistochemical staining results. Immunofluorescent staining demonstrated that the changes of the ratio of CB2R positive cells in neurons, CB2R positive cells in monocytes and CB2R positive cells in astrocytes to the total cell number showed a single peak pattern, which peaked at 12 h, 1 d and 7 d post-injury, respectively. Conclusion The expression of CB2R after brain contusion in neurons, monocytes and astrocytes in mice suggests that it is likely to be involved in the regulation of the biological functions of those cells. The changes in CB2R are time-dependent, which suggests its potential applicability as a biological indicator for wound age estimation of brain contusion in forensic practice.