Protective Effects And Mechanism Of Dulaglutide On Learning And Memory Of AD Mice

Objective:The research aims to investigate the protective effects and its mechanism of Dulaglutide on streptozotocin(STZ)intraventricμlar injection-induced sporadic AD model mice and APP/PS1/Tau transgenic(3×Tg)mice by intraperitoneal and intraventricμlar injection of two different modes of administration.Methods:(1)SPF 9-week-old male wild-type C57/BL6 mice were randomly divided into wild control group(CON),model group(STZ),Dulaglutide treatment group(Dul)and Dulaglutide+Ex9-39 group(Ex)and 10 in each group.The mice were adjusted to the environment for one week before modeling,and then the STZ group,Dul group and Ex group mice were subjected to two repeated bilateral ventricμlar injections of STZ(3mg/kg)to establish a sporadic AD model.After three weeks of modeling,the experiment was performed.The mice in the Dul group were intraperitoneally injected with Dulaglutide 12 μmol/kg(diluted with sterile saline),and Dulaglutide 12 μmol/kg and 0.8 g/kg of Ex9-39 were given to the mice in the Ex group.The CON group and the STZ group mice were intraperitoneally injected with the same amount of sterile saline for 4 weeks.The body weight of the mice was monitored weekly and the blood glucose of the mice was recorded before,during and end of the experiment.The spatial learning and memory ability of the mice was evaluated by Morris Water Maze.The phosphorylation of neurofilaments(NFs)and Tau protein were detected by western blotting and immunofluorescence.And synapse,Aβ,GLP-1 and GLP-1R and their GLP-1 downstream signaling pathway proteins PI3 K,AKT,GSK3β,CREB were checked by western blotting.Nissl staining of mice brain tissue labeled Nissl bodies and Golgi stained marked mouse cerebral cortical neurons and synapses.(2)SPF 9-week-old male wild type C57/BL6 mice and SPF 9-week-old male APP/PS1/Tau triple transgenic(3×Tg)mice were randomly grouped.Wild-type C57/BL6 mice were randomly divided into wild control group(CON),model group(STZ),low-dose Dulaglutide group(Dul(L),4 μ mol/kg),high-dose Dulaglutide group(Dul(H),12 μmol/kg),low-dose Dulaglutide+Ex9-39 group(Dul(L)+Ex,4μ mol/kg+0.8 g/kg),high-dose Dulaglutide+Ex9-39 group(Dul(H)+Ex,12 μmol/kg+0.8 g/kg)and Ex9-39(Ex,0.8 g/kg)group.Except for the CON group mice,others groups were treated with repeated bilateral ventricμlar injection of STZ(3mg/kg)to establish a sporadic AD model like the first part experiment.After three weeks of modeling,Each group of mice was injected Dulaglutide once a week in the ventricle.The CON group mice were injected with the same volume of sterile saline for 4 weeks.The body weight of the mice was monitored weekly and the blood glucose of the mice were recorded at before,during and before the experiment.The spatial learning and memory ability of the mice was evaluated by Morris water maze.The phosphorylation levels of Tau protein and NFs,synapsin and GLP-1 downstream signaling pathway proteins PI3 K,AKT,GSK3β in the brain of the mice were detected by Western blotting.Nissl staining of mouse brain labeled Nissl bodies and Golgi-stained marked mice cerebral cortical neuron cells and synapses.SPF9-week-old male 3×Tg mice were randomly divided into wild control group(CON),transgenic control group(Tg),Dulaglutide group(Dul,4 μmol/kg),and duaglutide+Ex9-39 group(Dul+Ex,4 μmol/kg+0.4 g/kg),Ex9-39 group(Ex,0.4g/kg).CON group mice were injected with equal volume of sterile saline for 4 weeks.The body weight of the mice was monitored weekly and the blood glucose of the mice before and before the treatment was recorded.The spatial learning and memory ability of the mice was evaluated by Morris water maze.The tau protein and NFs in the brain of the mice synapsin and its GLP-1 downstream signaling pathway protein GSK3β were detected by Western blotting.Golgi staining of mouse cerebral cortical neurons and synapses.Conclusion:Dulaglutide significantly improved AD-like neurodegeneration,which is possibly relative to the improvement of GLP-1 signaling pathway.And it maybe a new prospect in the clinical future.