P75NTR裂解抑制剂对CPZ诱导脱髓鞘小鼠认知功能及海马髓鞘的改善作用

Effect of P75NTR Cleavage Inhibitor on Cognitive Function and Myelin Sheath in Hippocampus of Cuprizone-induced Demyelination Mice

目的探究P75神经营养素受体(neurotrophin receptor P75,P75NTR)裂解抑制剂对双环己酮草酰二腙(cuprizone,CPZ)诱导脱髓鞘小鼠认知功能及海马髓鞘的改善作用。方法采用连续喂食0.2%CPZ的方法构建急性脱髓鞘模型(CPZ小鼠),同时设立对照组;5周后,在CPZ小鼠海马区注射P75NTR裂解抑制剂或生理盐水。在第6周,通过水迷宫、高架十字迷宫实验检测小鼠行为学的改变;通过快蓝染色检测髓鞘脱失情况;通过Western blot检测海马组织中P75NTR及髓鞘碱性蛋白(myelin basic protein,MBP)的表达变化;通过免疫组织化学检测海马组织中MBP阳性表达量的变化。结果与对照组相比,CPZ小鼠逃避潜伏期增加,跨台次数、进入开臂及在开臂中活动时间减少(P均<0.05);快蓝染色结果显示,CPZ小鼠胼胝体区髓鞘结构疏松,着色明显变浅;CPZ小鼠海马区P75NTR表达增加(P<0.05);CPZ小鼠海马区MBP表达减少(P<0.05)。相比于生理盐水的干预,P75NTR裂解抑制剂干预后,小鼠逃避潜伏期降低,进入开臂及在开臂中活动时间增加(P均<0.05);P75NTR裂解抑制剂干预后,小鼠海马区MBP表达上升(P<0.05)。结论抑制P75NTR的裂解可以改善CPZ模型小鼠的认知功能障碍,其作用机制与减轻海马中髓鞘脱失有关。

Objective To investigate the effect of neurotrophin receptor P75(P75NTR)cleavage inhibitor on cognitive function and myelin sheath in hippocampus of demyelinating mice model induced by cuprizone(CPZ).Methods Acute demyelination model(CPZ mice)was established by continuous feeding with 0.2%CPZ,and a Control group was set up.After 5 weeks,CPZ mice were injected with P75NTR cleavage inhibitor or normal saline in the hippocampus.In the 6th week,the changes of mice behavior were detected by Morris Water Maze and Elevated Plus Maze.Fast blue staining was used to study the change of myelin sheath in the corpus callosum.The expressions of P75NTR and myelin basic protein(MBP)in hippocampus were detected by Western blot.Immunohistochemistry was used to detect the change of MBP positive expression in hippocampus.Results Compared with the Control group,CPZ mice showed increased in the escape latency,and decreased the number of platform crossing,entering the open arm,and the time spent in the open arm(P all<0.05).The fast-blue staining results showed that the mouse treated with CPZ presented demyelination in the corpus callosum,the coloring is obviously lighter.The expression of MBP in the hippocampus of CPZ group was decreased,while the expression of P75NTR was increased(P<0.05).Compared with saline intervention,the mice treated with P75NTR cleavage inhibitor showed decreased escape latency,and increased the number of entering the open arm,and the time spent in the open arm(P all<0.05).The expression of MBP in the hippocampus of mice were increased after DAPT intervention(P<0.05).Conclusion Inhibition of P75NTR cleavage can improve cognitive dysfunction in cuprizone model mice,and the mechanism is related to the alleviation of demyelination in the hippocampus.