| Objective: With the intensification of population aging,how to delay aging and promote health is an important public health problem facing the world.Dietary restriction(DR),physical regulation and other non-drug interventions have become important anti-aging measures.They can not only interfere with the normal physiological aging process,but also affect the pathological aging process such as Alzheimer’s disease(AD).Studies have shown that DR can prolong the life of model animals and delay brain aging by improving mitochondrial function and synaptic plasticity.In addition,physical interventions such as transcranial direct current stimulation(tDCS)can regulate brain aging through mechanisms such as cortical excitability and neural plasticity.The study found that these non-drug interventions can affect the cognitive impairment caused by physiological or pathological brain aging.However,the existing brain aging intervention research has made more progress in functional type and less progress in mechanism type,and the research on the combination of mechanism and function is very limited.Moreover,the impact of these interventions on behavioral cognition in young animals is also controversial.This study aims to explore the effects of DR and physical intervention on early physiological or pathological brain aging in mice,and mainly study the molecular mechanism of behavioral cognitive changes in mice from the perspective of brain transcriptome.Methods: In the study of dietary intervention,firstly,the effect of DR on early normal aging mice was discussed,and the age,gender and degree of food restriction were compared.The subjects were young(2-3 months),middle-aged(7-9 months)and middle-aged(10-11 months)male and female mice,and DR(0%,20%,40%)lasted for 2 months;Secondly,to explore the effect of DR on pathological brain aging AD mice(2-3 months old).DR(0%,30%)lasted for 4.5 months.In the physical intervention study,the effects of tDCS(300 μ a,20 min,5 days)on AD mice(8-12 months old)and the effects of gamma aminobutyric acid(GABA)receptor inhibition(PTX,0.18mg/ml,i.p.)on tDCS were discussed.The main research methods were transcriptome sequencing and behavioral cognitive testing of prefrontal cortex(PFC)and hippocampus(Hip).Transcriptome sequencing mainly included differential expression gene(DEG)analysis,function and pathway enrichment analysis,and glutamate(Glu)-GABA excitation/inhibition balance gene set analysis and analysis of Aging-related genes.The behavioral cognition experiment was mainly carried out by using the paradigms of Barnes maze,Y maze,open field and elevated cross maze to detect the learning and memory,anxiety,exploration and motor ability of mice.In the above experiments,the behavioral cognition test of AD mice is the preliminary work of the laboratory(completed by Shuangshuang Wu and Mengsi Duan in 2019).This study focuses on analyzing the possible mechanism of behavioral cognition change of mice in combination with transcriptome data.Results: In the dietary intervention,firstly,the effect of DR on normal early brain aging was analyzed.Transcriptome:(1)age: with the increase of age,the number of DEG caused by DR in PFC and hip decreased gradually,and the number of DEG in PFC was higher than that in hip,especially in young female mice;Pathway enrichment showed that DR down regulated the inflammatory response,glutamatergic synapse,GABAergic synapse and long-term inhibitory effect related pathways in young mice,as well as the long-term inhibitory effect and the regulation pathway of middle-aged and young mice in three age groups;Up regulate AMPK pathway in young and middle-aged mice,m TOR pathway and circadian rhythm pathway in young and middle-aged mice.(2)Gender: compared with females,DR has a higher number of DEG caused by hip in young male mice.Pathway enrichment shows that Dr mainly up regulates the circadian rhythm pathway of young male mice and down regulates the pathways related to glutamatergic synapse,long-term enhancement effect and long-term inhibition effect;in young and middle-aged male mouse Hip,m TOR and Wnt pathways were up-regulated,nod-like signaling and carbohydrate digestion and absorption pathways were down-regulated.(3)Degree of food restriction: compared with 20% DR,40% DR has a large number of differential genes caused by hip in mice,mainly involving the down regulation of m TOR and TGF-β、Wnt and Hippo signaling pathways.(4)Further analysis of the Glu-GABA excitation/inhibition balance gene set showed that the expression of Gabrr2 gene was up-regulated in all groups,and other genes were down regulated.Glu and GABA pathways were more vulnerable to DR in young mice,and the changes before and after DR showed the opposite trend.(5)The results of aging-related gene analysis showed that a total of 13 longevity genes and 9 aging-related genes were detected in the three ages.Among them,the expression changes of longevity genes Trp73,Xpa and aging-related gene Akt2 were consistent in the PFC of the three ages.Trp73 and Xpa showed an up-regulation trend,while Akt2 showed a down-regulation trend.Behavioral cognition:(1)learning and memory: 20% DR has no significant effect on spatial memory ability,but it has damage on spatial learning ability;40%DR can damage both;(2)Anxiety level: 20% DR and 40% DR can alleviate the anxiety level of middle-aged,young and middle-aged mice to a certain extent;(3)Exploration and exercise ability: 40% DR has damage to the exploration ability of young and middle-aged male mice and the exercise ability of young male mice and young and middle-aged mice.Secondly,analyze the early intervention effect of DR on AD.DR caused more differential genes in female mice(1.8%),mainly down regulating the complement system.DR did not change the genes related to Glu-GABA excitation/inhibition balance in male and female mice.Similarly,the pre laboratory behavioral results showed that 30% DR had no significant effect on the learning and memory and anxiety level of mice.Finally,the effect of tDCS on mice before and after GABA inhibition was analyzed in physical intervention.After tDCS stimulation,the number of hip differentially expressed genes accounted for 0.72%,and after injection of GABA receptor antagonist PTX and anode stimulation,the number of differentially expressed genes accounted for only 0.44%;Gene pathway analysis showed that tDCS anode stimulation mainly affected the metabolic process,while the immune response process showed a downward trend after PTX injection;Further analysis of the Glu-GABA excitation/inhibition balance gene set showed that the GABA transporter Slc6a13 gene was significantly down regulated after tDCS stimulation.Similarly,the pre laboratory behavioral results suggest that tDCS stimulation may affect the behavioral cognition of mice through GABA system.tDCS stimulation can improve the long-term spatial memory ability of AD mice,and stimulation after PTX injection will block this improvement.Conclusion:(1)DR will cause damage to the behavioral cognition related to normal early brain aging.The degree of damage is related to the degree of food restriction,and has age and gender differences.The damage mechanism may be related to DR down regulating glutamatergic synapse,GABAergic synapse,long-term enhancement and long-term inhibition effect pathway,and up regulating m TOR pathway.The early intervention of DR on pathological brain aging such as AD did not improve the related behavioral cognition,and there was no change in the functional pathway related to behavioral cognition in the transcriptome.(2)Physical intervention such as tDCS can improve the behavioral cognition after the onset of pathological brain aging AD,and its improvement mechanism may be related to the down-regulation of GABA transporter Slc6a13 gene. |
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