| Objectives: Alzheimer’s disease(AD)is the most common type of senile dementia.The pathogenesis of AD is unclear,and mitochondrial dysfunction plays an important role in the pathogenesis of AD.Mitochondria are the main place where cells carry out aerobic respiration,and are the body’s "energy factory",which is responsible for the energy supply of life.The accumulation of Aβ in the neurons of AD patients can inhibit key enzymes in the mitochondrial metabolic chain,which leads to the mitochondrial dysfunction or damage.When the mitochondria in neurons are damaged,on the one hand,it will promote the body to clear the damaged mitochondria through the autophagy pathway to maintain physiological homeostasis;on the other hand,it can also cause a series of mitochondrial metabolic disorders especially in neurodegenerative diseases such as AD.Reduced mitochondrial energy due to metabolism disorder will further promote the accumulation of mitochondrial autophagosomes,and lead to the death of neurons.So,the aim of this experiment is to explore the mechanism of neuronal mitochondria damage in the hippocampus of different age APP/PS1 double transgenic AD mice,and to explore the related metabolites and metabolic pathways for further understanding the pathogenesis,so as to provide new ideas and strategies for the treatment of AD.Methods: Male APPswe/PSEN1de9 double transgenic AD mice were selected for the study.After gene identification,randomly divide 24 AD mice into there-month group,six-month group,nine-month group and twelve-month group.C57 BL wild-type mice served as the control group.Morris water maze was used to test the ability of learning and memory and spatial exploration.Electron microscope observation of mitochondrial damage and autophagosome accumulation.Western blot was used to detect the expression levels of LC3 and p62,PINK1,Parkin and Miro1 and Tom 20.The metabolites in hippocampus were detected by GC-MS.Results: Morris water maze experiment showed that the escape latency of the wild-type group was higher than that of the APP/PS1-6M and APP/PS1-12 M groups of the experimental group in the positioning and navigation experiment.Similarly,in the sailing distance experiment,the sailing distance of wild type、APP/PS1-3M and APP/PS1-6M groups decreased gradually with the increase of test days.In the space exploration experiment,the wild type group had higher average times of crossing the platform area than the APP/PS1-9M and APP/PS1-12 M groups.There was no obvious abnormality and autophagosome accumulation of mitochondria in the hippocampus in the wild type and APP/PS1-3M groups under electron microscope,while the APP/PS1-6M,APP/PS1-9M and APP/PS1-12 M groups suffered serious damage of mitochondrial edema,and the accumulation of autophagosome gradually increased.Western blot analysis of autophagy-related protein LC3 and P62 showed that the expression levels of in APP/ PS1-6M,APP/PS1-9M and APP/PS1-12 M groups were higher than those of Wild type group(P< 0.05),the expression level of Miro1 in APP/ PS1-6M,APP/ PS1-9M and APP/ PS1-12 M groups was lower than that in Wild type group(P <0.05).There was no differential expression level of Tom20 in each group(P>0.05).GC-MS detection and analysis of the metabolites in the hippocampus of each group showed that the level of succinic acid in the APP/PS1-6M group increased significantly(P <0.05),and the many metabolites of the APP/PS1-9M group were significantly increased.Among them,Citric acid levels rose significantly(P <0.05).Glycolytic pathways are the mainly metabolic pathways related to mitochondria.Conclusion: The cognitive impairment of APP/PS1 double transgenic AD mice gradually aggravated with increasing age,and the damage of mitochondria in hippocampal neurons was also gradually aggravated,accompanied by the accumulation of autophagy.Although mitochondrial autophagy was enhanced,it was accompanied by mitochondrial clearance disorder,which leads to the disorder of material metabolism closely related to mitochondrial function. |
PDF Full Text Request