| Background:Alzheimer's disease(AD),a progressive development central nervous system degenerative disease,has been gradually increasing worldwide.It often occurs in the population over 65 years of age,containing clinical manifestations of memory,spatial disorientation,personality changes,etc.It impacts patients' living condition seriously.A great quantity medical care and fund support were provided,though there are still no highly individualized drugs and practical strategies for clinical prevention and treatment.Developmentally regulated brain protein(Drebrin,Dbn,also abbreviated as Dbn1 in mouse),existing in neurons especially in dendritic,is an actin binding protein to adjust synaptic morphology and long-term memory.However,majority of the studies focus on its upstream proteins,but lack of the impacts on the behavior and interaction of AD in vivo.Therefore,this study was designed to test the relationship between Drebrin in hippocampus and behavior performances in AD model(APPswe/PS1?E9,APP/PS1)mice,and the effect of high expression of Drebrin in hippocampus on AD mice.All the results are expected to provide some support for the prevention and treatment of AD.Methods:Here,we tracked the behavior performances including Morris water maze,open field test and novel object test in 4,8,12,16 months AD mice.And we investigated the expression level of Drebrin in hippocampus of these AD mice and 12months Wild-type(WT)mice by western blotting method.We analyzed the correlation between behavioral data of AD mice in different age and the corresponding Drebrin expression by Pearson correlation analysis.Subsequently,we injected rAAV9-Dbnl vectors into hippocampus of 2 months AD mice to maintain high expression in the injection area for long time.After 6 months,the injected AD mice,other age-matched control AD and WT mice were conducted behavioral test,some of them were randomly selected to perform small animals MicroPET/CT to inspect brain glucose metabolism.Hippocampal and cortical regions were selected as regions of interest(ROI)to determine glucose utilization.And then the mice brain were extracted and used for pathology detection by immunohistochemistry or immunofluorescence staining method,including Drebrin level in mice hippocampus,Amyloid ?(A?)plaque,astrocytes,Filamentous actin(F-actin),N-methyl-D-aspartic acid-type glutamate receptor 1(NMDAR1),microtubule-associated protein 2(MAP2)and synapsinl(Synl).Results:We found that the ability of learning and memory and spatial exploration in 4-16 months AD mice decreased significantly with age,the frequency of rearing in open field and Discrimination Index(DI)in novel object test were also decreased significantly.The results of Western blot showed that expression level of Drebrin decreased with age.Pearson correlation analysis showed Drebrin was significantly correlative with behavior performances in these adult AD mice.Increased positive of Drebrin protein were observed in hippocampus of rAAV9-Dbn1 injection AD mice.In addition,we found a better behavioral performance in this injection group.MicroPET/CT showed that the rate of glucose uptake in the area of interest(ROI)was higher than that of control AD mice.Pathological detection revealed that A? plaque and GFAP reduced noticeably in their hippocampus.F-actin and MAP2 increased markedly.There was no significantly change of NMDAR1 and Syn1 in hippocampus of rAAV9-Dbn1 injection mice.Conclusion:The expression level of Drebrin protein in adult AD mice decreased with age especially in 12-16months.Behavioral test results showed that the cognitive ability and spatial exploration ability of AD mice decreased significantly with age.The results of correlation analysis showed that there were significant correlations between expression level of Drebrin in hippocampus and the behavior performances in AD mice with different ages.The cognitive ability and glucose utilization of AD mice with high expression Drebrin in hippocampus was significantly improved than that in control AD mice.A? plaque and activated astrocytes reduced markedly in hippocampus of rAAV9-Dbn1 injection AD mice.Neuronal microtubule-associated protein and F-actin were significantly increased in hippocampus of these injection mice.An effective expression of Drebrin may promote MAP2 to stabilize the structure and function in neuronal dendrites and improve memory in mice by modulating the interaction of F-actin and neural microtubules.The results may provide some valuable resources for gene therapy and research of AD.Background:Developmentally regulated brain protein(Drebrin,Dbn)is a kind of actin binding protein and widely distributes in brain neuron especially dendritic spines.It is found that it plays an important role in cell migration,synaptic development and plasticity.Hippocampal LTP memory activities are associated with synaptic remodeling.During this process,the excitatory postsynaptic potential increase and maintain for several hours under the stimulation.Drebrin,which has a function of maintaining LTP memory,can form complex with filamentous actin in the postsynaptic density.Although Drebrin is distributed in many regions of brain,the hippocampus is the main region.Drebrin abnormalities are common in some cognitive disorders,so it is often used to evaluate the situation of memory associated diseases.Drebrin deletion has been studied in Wild-type mice,the molecular changes in the brain of mice were observed by electrophysiological and pathological experiments.However,there is still lack of experimental evidence of behavior and glucose metabolism,and the studies in transgenic mice such as AD mice were still not reported.It was found noticeably decline in hippocampus and cortex in Alzheimer's disease(AD)patients.However,the relationship between Drebrin and AD need more detailed explore.Additionally,it is still not clear whether the Down-regulated Drebrin is a key factor to impact progression of AD.Methods:Here,we injected Drebrin interference vector(rAAV-mDbnl ShRNA)in hippocampus of 3months APP(swe)/PS 1(?E9)mice(APP/PS1 mice),and then successfully Down-regulated Drebrin expression in this target region.The same volume of rAAV plasmid was injected into same site of age-matched AD mice as APP/PS1-control group.The mice including AD and WT were reared under the same conditions.Behavioral tests including Morris water maze test(MWM),open field test and novel object test were performed when the mice nearly 9 months old.Subsequently,MicroPET/CT using 2-deoxy-2-[18F]fluoro-D-glucose(18F-FDG)to detect glucose metabolism was conducted.We selected hippocampus as ROI to detect glucose uptake.Finally,the mice brain tissue was used to investigate A?,GFAP,PSD-95,MAP2,vimentin,Cox43 and Synl by immunohistochemical or immunofluorescence methods to explore the impact of decreased Drebrin in hippocampus.Results:Our results showed that AD mice with a low expression of Drebrin performed poor in behavioral tests mainly for learning and memory ability especially the time spent in target quadrant is shortened in the probe test,and had decreased glucose utilization in hippocampus by MicroPET/CT inspection.In addition,there were a little scale increase of A? and GFAP and significantly decline of PSD-95 and MAP2.A noticeably increase of vimentin were found in down-regulated Drebrin AD mice.There was no significant change of Cox43 and Synl in hippocampus of low expression Drebrin AD mice.Conclusion:Down-regulation of Drebrin in hippocampus of AD mice reduced cognitive capability.Lack of Drebrin decreased brain glucose utilization in hippocampus.Down-regulated Drebrin in hippocampus of AD mice reduced PSD-95 and MAP2.Lack of Drebrin activated astrocytes,increased A? and vimentin.Down-regulation of Drebrin may aggravate pathological impairment of AD.This finding may provide some evidences for AD research and treatment. |
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