Neuroprotective Effects Of GLP-1/GIP/Gcg Triagonist On APP/PS1 Transgenic Mice

Background:Alzheimer's Disease(AD)is a progressive neurodegenerative disease,characterized clinically by progressive memory loss,cognitive decline,and aberrant behavior.Currently,there is no treatment can improve this condition.Epidemiological studies have shown that type 2 diabetes mellitus(T2DM)is a risk factor for Alzheimer disease(AD).Both of them have many common pathological features.This motivated research in drugs that have shown good effects in treating diabetes to investigate if they could be helpful in treating AD as well.Previous studies have shown that the incretin hormones glucagon-like peptide-1(GLP-1)and glucose-dependent insulinotropic polypeptide(GIP)can play a neuroprotective role in the brain and show very promising effects in animal models of AD.Recent studies show that GLP-1/GIP/Gcg triagonist(Triagonist)can simultaneously activate GLP-1,GIP,and Gcg receptors and have a long biological half-life in the treatment of T2 DM.The effect is remarkable in animal experiments.However,no studies have been published that test the neuroprotective effects of this novel drug.We therefore tested this promising Triagonist in the APP/PS1 mouse model of AD.This mouse model recapitulates some of the hallmarks of AD.Objective:1.To observe whether Triagonist can improve the impairment of working and spatial learning and memory abilities of APP/AP1 transgenic mice and partially reverses cognitive decline.2.To investigate whether Triagonist can reduce the total amount of b-amyloid and whether it has anti-oxidative and anti-inflammatory effects.3.To investigate whether Triagonist could increase the numbers of SYN,regulate brain-derived neurotrophic factor(BDNF),and promote the expression of apoptosis-related proteins,and enchance the DCX.Methods:1.Animals and drug treament: 12 male 6-month-old C57BL/6 mice and 24 male APP/PS1 transgenic mice were randomly divided into three groups: 1)Control group: C57BL/6J mouse + Saline;2)APP/PS1 group: APP/PS1 transgenic mice + Saline;3)Treatment group: APP/PS1 transgenic mice + Triagonist,12 in each group.The treatment group was intraperitoneally injected with Trigonist 10nmol/kg daily.The control group and APP/PS1 group were injected intraperitoneally with the same volume of physiological saline(0.9%)daily.The daily injection time was 8:00-9:00 am for two months.2.Behavioral assessment: Morris water maze test was performed after two months,continuous injection was operated to observe the behavioral changes in mice.3.Sample preparation: All mice were sacrificed after behavioral experiments being completed.Each group of 6 rats was fixed with paraffin sections and used for immunohistochemical staining.The remaining 6 rats in each group were isolated from fresh hippocampus and used for Western Blot experiments.4.Immunohistochemical staining was used to detect the expression of A?,GFAP,IBA-1,4-HNE,8-OHdG and DCX in hippocampus of cortex and hippocampus in each group.5.Western blot was used to detect the expression of BAX,Bcl-2,BDNF,SYN and DCX in the hippocampus of each group.Results:1.Morris water maze test: APP/PS1 have significant lower memory behavior scores in spatial water maze task than control group.Compared with APP/PS1 group,Triagonist could improve memory deficit.2.The positive expression of A?,GFAP,IBA-1,4-HNE and 8-OHdG in the cortex and hippocampus of the APP/PS1 model group was significantly higher than that of the control group.Compared with the APP/PS1 group,the expression of A?,GFAP,IBA-1,4-HNE,and 8-OHdG were significantly decreased in the cortex and hippocampus of the treatment group.The positive expression of DCX in the APP/PS1 group was significantly lower than that in the control group.The positive expression of DCX in the hippocampus of the treated mice was significantly higher than that of the APP/PS1 group.3.Western blotting method examination results show: The expression of SYN and BDNF in hippocampus of APP/PS1 group were significantly lower than that of control group,while the ratio of BAX/Bcl-2 was significantly increased compared with the control group.After Triagonist treatment,the BAX/Bcl-2 ratio can be down-regulated,and it also enchance the expression of SYN,BDNF,and DCX.Conclusion:1.Triagonist can improve the impairment of spatial learning and memory ability in APP/PS1 mice and partially reverse cognitive decline.2.Triagonist can reduce amyloid plaque load,chronic inflammation and oxidative stress,as well as mitochondrial stress signaling.3.Triagonist can improved BDNF release and synaptic markers while normalising neurogenesis in the dentate gyrus and holds clear promise of being developed into a new treatment for chronic neurodegenerative disorders such as Alzheimer's disease.