| Purpose:1.Objective to explore the effect of 8-week moderate intensity exercise on cognitive function of type 2 diabetic mice,and to provide reference and guidance for diabetic patients to formulate appropriate exercise prescription.2.To verify the effect of 8 weeks of moderate intensity exercise on cognitive function of type 2 diabetic mice is related to the reduction of neuroinflammation by miR-146a/PrPC/Aβ pathway.Methods:Thirty six 8-week-old db/db mice were randomly divided into three Groups with 12 mice in each Group:quiet control Group(DA Group),moderate intensity aerobic exercise Group(DR Group)and moderate intensity resistance exercise Group(DP Group)Another 12 non-diabetic wild-type m/m mice of the same week age were used as normal quiet control Group(MA Group DA Group and MA Group did not intervene,only normal physiological activities.The mice in DR Group and DP Group were given moderate intensity exercise training for 8 weeks.Before the formal intervention,they were given adaptive exercise training for one week.The DR Group was intervened 5 times a week for 45 minutes with the intensity of 10 m/min.The DP Group was intervened three times a week,each time climbing three Groups,with an interval of 2 minutes.There was no weight-bearing in the first week,the tail weight-bearing in the second week was 20%,the tail weight-bearing in the third to fourth weeks was 30%,the tail weight-bearing in the fifth to sixth weeks was 40%,and the tail weight-bearing in the seventh to eighth weeks was 50%.Body weight and fasting blood glucose detection(FBG)were measured once a week at a fixed time.Open field and Morris water maze tests were performed after 8 weeks of exercise.Fasting for 12 hours was performed after the test.The brain tissues of 3 rats in each Group were perfused with formaldehyde,and the synaptophysin,PrPC,Aβ,Iba1 were detected by frozen section fluorescence staining;the cell morphology of hippocampus was observed by HE staining.Fresh hippocampal tissue was obtained from 3 mice in each Group,and exosomes were identified by nanoparticle tracking analysis(NTA);microglia derived exosomes were sorted by magnetic beads;the expression of miR-146a in hippocampal tissue and microglia derived exosomes was detected by real-time fluorescent quantitative PCR.The expression of PrPc and Aβ protein was detected by Western blot.Results:1.General information(1)Body weight:the body weight of mice in each Group was significantly higher at 8W than that at OW(P<0.01 or P<0.05).The weight of DA mice was significantly higher than that of MA Group at 0W and 8W(P<0.01);the weight of DR Group and DP Group was significantly lower than that of DA Group after moderate intensity exercise(P<0.01 or P<0.05),and the effect of DR Groupon weight control was the best.(2)Fasting blood glucose(FBG):there was no significant difference in the fasting blood glucose of Ma normal control Group(P>0.05);the fasting blood glucose of db/dbmice in DA Group,DR Group and DP Group increased significantly after 8 weeks(P<0.05 or P<0.01).The fasting blood glucose of DA Group was significantly higher than that of MA Group at 0W and 8W(P<0.01);the fasting blood glucose of DR Group and DP Group was significantly lower than that of DA Group after 8W moderate intensity exercise(P<0.01);there was no significant difference between DR Group and DP Group after 8W moderate intensity exercise(P>0.05).2.Cognitive function(1)Short term memoryPercentage of new object exploration time:the percentage of new object exploration time in DA Group was significantly lower than that in MA Group(P<0.01);the percentage of new object exploration time in DR Group and DP mice was significantly higher than that in DA Group after 8 weeks of moderate intensity exercise(P<0.01);there was no significant difference in the percentage of new object exploration time between DR Group and DP mice(P>0.05).(2)Spatial cognitive abilitya.The escape latency:The escape latency of DA Group was significantly higher than that of MA Group(P<0.01);after 8 weeks of moderate intensity exercise,the escape latency of DR Group and DP Group were lower than that of DA Group,and there was significant difference between DR Group and DA Group(P<0.05);there was no significant difference between DR Group and DP Group(P>0.05).b.Swimming speed,percentage of target quadrant time and times of crossing platform:The swimming speed,percentage of target quadrant time and times of crossing platform of DA Group were significantly lower than those of MA Group(P<0.01);after 8 weeks of moderate intensity exercise,the swimming speed,percentage of target quadrant time and times of crossing platform of DR Group and DP Group were higher than those of DA Group There were significant differences in the three indexes(P<0.05 or P<0.01);there were no significant differences in the three indexes between DR Group and DP Group(P>0.05).3.Pathomorphology(1)HE staining:in MA Group,the cells were evenly distributed,the size of nucleus was symmetrical,and the number of cell layers was more.The results showed that the pyramidal cells in CA1 area of hippocampus in DA Group were loose and disordered,the cell layers were less,the extracellular space was obvious,the nucleus size was uneven,and some nuclei were pyknosis;after 8 weeks of exercise,the pyramidal cells in CA1 area of hippocampus in DR Group and DP Group were loose and disordered,compared with DA Group,the number of pyramidal cells in CA1 area of hippocampus in DA Group was lower than that in MA Group(P<0.01);After 8 weeks of exercise intervention,the number of pyramidal cells in hippocampal CA1 area of DR Group and DP Group was significantly higher than that of DA Group(P<0.01);there was no significant difference between DR Group and DP Group(P>0.05).(2)Immunofluorescence of synaptophysin:the expression of synaptophysin in hippocampal CA1 area of DA Group was significantly lower than that of MA Group(P<0.01);the expression of synaptophysin in hippocampal CA1 area of DR Group and DP Group was significantly higher than that of DA Group(P<0.01);but there was no significant difference between DR Group and DP Group(P>0.05).4.Neuroinflammation in hippocampusMicroglia activation:the microglia activation in hippocampal CA1 area of DA Group was significantly higher than that of MA Group(P<0.01);the microglia activation in hippocampal CA1 area of DR Group and DP Group was significantly lower than that of DA Group(P<0.05 or P<0.01);compared with Dr Group,the microglia activation in hippocampal CA1 area of DP Group was significantly higher than that of DR Group(P<0.05).5.Related indicators of neuroinflammatory pathway(1)MiR-146a and microglia derived exocrine in hippocampus:the expression of miR-146a and microglia derived exocrine in hippocampus of DA Group was significantly lower than that of MA Group(P<0.01);the expression of miR-146a and microglia derived exocrine in hippocampus of DR Group and DP Group was significantly higher than that of DA Group(P<0.01);the expression of miR-146a and microglia derived exocrine in hippocampus of DR Groupwas significantly higher than that of DA Group(P<0.01)The expression of miR-146a in cell-derived exocrine was significantly higher than that in DP Group(P<0.05);the expression of miR-146a in hippocampus was positively correlated with that in microglia derived exocrine.(2)PrPc and Aβ protein:the gray value of PrPC and Aβ protein expression in DA Group was significantly higher than that in MA Group(P<0.01);the gray value of PrPC and Aβprotein expression in DR Group and DP Group was significantly lower than that in DA Group(P<0.01);the gray value of PrPC protein expression in DR Group was significantly lower than that in DP Group(P<0.05);there was no significant difference in the gray value of Aβ protein expression between DR Group and DP Group(P>0.05).Conclusions:1.8 weeks of moderate intensity exercise can improve the cognitive function of type 2 diabetic mice2.The mechanism of exercise intervention in improving diabetic cognitive impairment is related to the inhibition of neuroinflammation by microglia derived exosomes miR-146a/PrPC/Aβ pathway... |
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