咖啡酸苯乙酯通过抑制mGluR5-Fyn信号通路改善5×FAD小鼠认知功能OA

AIM:To investigate the dynamic changes of metabotropic glutamate receptor 5(mGluR5)-Fyn signaling pathway in the hippocampus of 5×familial Alzheimer disease(FAD)mice,and the regulatory effects of caffeic acid phenethyl ester(CAPE)on cognition and related signaling pathways in mice.METHODS:Wild-type(WT)mice,5×FAD transgenic mice and 5×FAD/mGluR5 gene heterozygous knockout(mGluR5+/-)mice were used.The mice were di-vided into WT group,WT+CAPE group,5×FAD group,and 5×FAD+CAPE group(6-month-old 5×FAD mice were given intraperitoneal injection of CAPE for 30 consecutive days).The WT and 5×FAD mice at different months of age were se-lected to detect disease course-related indicators,while 6-month-old WT,5×FAD and 5×FAD/mGluR5+/-mice were select-ed to verify the regulatory relationship between mGluR5 and Fyn.Morris water maze(MWM)test,novel object recogni-tion(NOR)test and passive avoidance test(PAT)were used to evaluate cognitive function.Western blot was used to de-tect the protein expression of mGluR5,the phosphorylation levels of p-Fyn(Tyr416)and downstream signaling molecules[protein kinase C(PKC),extracellular signal-regulated kinase(ERK),nuclear factor-κB(NF-κB)and inhibitor of NF-κB kinase(IKK)],and the expression of cognition/synapse-related proteins[postsynaptic density protein 95(PSD95),microtubule-associated protein 2(MAP2),neuronal nuclear antigen(NeuN)and synaptophysin(SYP)]in the hippocam-pus,to verify the regulatory relationship between mGluR5/Fyn and the effect of CAPE.RESULTS:(1)Compared with WT mice of the same month of age,the expression level of mGluR5 in the hippocampus of 5×FAD mice at 6,8,10 and 12 months of age was significantly increased(P<0.01),and the phosphorylation level of Fyn was significantly up-regulated(P<0.05 or P<0.01).Compared with 5×FAD mice,the expression level of mGluR5 in 6-month-old 5×FAD/mGluR5+/-mice was significantly decreased(P<0.01),and the phosphorylation level of Fyn was significantly decreased(P<0.01).(2)Compared with 5×FAD group,the behavioral indicators of MWM,NOR and PAT in 5×FAD+CAPE group were signifi-cantly improved(P<0.01),and the cognitive function was significantly recovered.(3)Treatment with CAPE significant-ly down-regulated the abnormal expression of mGluR5(P<0.01)and excessive phosphorylation of Fyn(P<0.05),and sig-nificantly up-regulated the expression of PSD95,MAP2,NeuN and SYP in the hippocampus of 5×FAD mice(P<0.05).(4)The levels of p-PKC,p-IKK and p-NF-κB in the hippocampus of 5×FAD+CAPE group were significantly decreased(P<0.05 or P<0.01),while the level of p-ERK was significantly increased(P<0.05),and the synaptic structure damage was repaired.CONCLUSION:The expression of mGluR5 and the phosphorylation of Fyn in the hippocampus of 5×FAD mice are abnormally up-regulated during different disease courses,and mGluR5 can regulate Fyn activation.Treatment with CAPE attenuates synaptic damage,neuroinflammation and cognitive impairment in 5×FAD mice through mGluR5-Fyn signaling pathway,suggesting that CAPE is a potential anti-Alzheimer disease candidate compound.