基于α-synuclein表达探讨七氟烷对小鼠树突棘状态与学习记忆功能的影响

Effects of Sev of lurane on dendritic spines as well as learning and memory function in mice viaα-synuclein

目的探讨七氟烷对小鼠树突棘状态与学习记忆功能的影响与机制。方法16只野生型小鼠与16只α-synuclein基因敲除小鼠,共分为4组,分别为WT Control组,KO Control组,WT+Sev组与KO+Sev组。其中WT+Sev组与KO+Sev组小鼠连续吸入6 h 3%七氟烷(Sevoflurane,Sev)麻醉。利用水迷宫检测小鼠学习记忆功能,处死后检测小鼠海马CA3-CA1途径中长时程电位与树突棘状态,再检测小鼠海马组织中α-synuclein、BDNF与TrkB表达水平。体外细胞实验中,利用HT22细胞株确定α-synuclein、BDNF与TrkB竞争性结合机制。结果与对照组相比,Morris水迷宫结果表明七氟烷造成小鼠逃避潜伏期延长(P<0.05),穿越平台次数减少(P<0.05),靶象限停留时间减少(P<0.05);七氟烷导致小鼠海马CA3-CA1途径中长时程电位抑制且树突棘密度降低(P<0.05);此外,七氟烷造成小鼠脑组织中α-synuclein表达增加(P<0.05)且BDNF与p-TrkB表达降低(P<0.05);与此同时,Morris水迷宫测试中,与WT+Sev组相比,KO+Sev组小鼠结果较优,但仅有测试中逃避潜伏期有显著性差异(P<0.05);KO+Sev组小鼠海马组织中长时程电位显著升高且树突棘密度增加(P<0.05);KO+Sev组小鼠海马组织中BDNF、p-TrkB表达显著升高(P<0.05)。体外实验中,Sev造成HT22细胞活率降低,且显著增加了α-synuclein与TrkB邻位连接(P<0.05)。结论七氟烷会造成小鼠学习与记忆功能损伤,其机制为增加α-synuclein表达,下调BDNF水平,减少TrkB磷酸化水平,减少树突棘密度从而抑制长时程电位。

Objective To investigate the effect and mechanism of Sev oflurane(Sev)on dendritic spines as well as learning and memory in mice.Methods Sixteen wild-type(WT)mice and 16α-synuclein knockout(KO)mice were divided into 4 groups,namely WT Control group,KO Control group,WT+Sev group and KO+Sev group.Mice in WT+Sev and KO+Sev groups were anesthetized by inhaling 3%Sev for 6 h.Morris water maze was used to detect the learning and memory function of mice.The long-term potentials and dendritic spines in hippocampus CA3-CA1 pathway were detected and the expression ofα-synuclein,BDNF and TrkB in hippocampus were measured.In addition,HT22 cell line was used to explore the binding mechanism ofα-synuclein,BDNF and TrkB.Results The results of Morris water maze showed that,compared with Control group,Sev caused the escape latency prolonged,the number of crossing platforms decreased,and residence time in the target quadrant decreased.However,Sev caused long-term potential inhibition in mouse hippocampus and decreased synaptic spine density.Also,Sev increased the expression ofα-synuclein in mouse brain tissue and decreased BDNF and phosphorylated-TrkB(p-TrkB)expression.At the same time,in Morris water maze detection,compared with WT+Sev group,the escape latency in KO+Sev group was attenuated.Moreover,the long-term potential and dendritic spine densityin KO+Sev group was increased.The expression of BDNF and p-TrkB in KO+Sev group was increased(P<0.05).In vitro studies indicated that Sev decreased the viability of HT22 cells and increased the proximity ligation ofα-synuclein and TrkB.Conclusion Sev causes learning and memory function impairment in mice.The mechanism might be related to increasing the expression ofα-synuclein,down-regulating the level of BDNF,reducing the phosphorylation level of TrkB,which ultimately reduces the density of dendritic spines and inhibit long-term potential.