| Objective: Alzheimer’s disease(AD),an age-related neurodegenerative disease of the central nervous system,is a more common form of senile dementia.With the accelerating pace of population aging,the prevalence of AD is increasing year by year.Its etiology is complex and diverse,and its pathogenesis is not yet clear,which brings great challenges to the research of prevention and treatment methods of AD.Studies have showed that synaptic function damage in AD patients is closely related to the damage of cognitive function.Synaptophysin(SYP)is a kind of phosphoprotein that binds to synaptic vesicles.It is a specific outer membrane protein closely related to synaptic plasticity.Current evidence suggests that SYP levels are decreased in hippocampi of AD patients.Therefore,regulating the expression of SYP is of great significance for restoring synaptic function and improving cognition.Micro RNA is a kind of single-stranded non-coding RNA exist in eukaryotic genomes.By complementary binding with its target.m RNA,it can lead to m RNA.degradation or play the function of inhibiting translation,.so as to negatively regulate gene expression.The abnormal expression.of micro RNA in brain tissue was found to be closely related to the course of AD patients.Bioinformatics analysis showed that mir-671 could inhibit the expression of SYP.In conclusion,the decrease of SYP in brains of AD patients may be antagonized by the down regulation of mir-671.Prebiotic is a dietary supplement that antagonizes AD through improving intestinal flora,anti-inflammation,anti-oxidation and other ways.As a probiotic,fructo-oligosaccharide(FOS)can increase the amount of intestinal bifidobacterium.Bifidobacterium can metabolize glutamic acid to produce gamma-aminobutyric acid(GABA),and the levels of GABA are significantly reduced in AD patients’ brains.Our previous studies have confirmed that GABA can down-regulate the expression of mir-671 in SH-SY5 Y cells.However,it is still unknown that whether FOS can improve the expression of SYP in AD then restore synaptic function and improve cognition through increasing GABA content in brains then down-regulating mir-671.This study first confirmed that FOS can improve cognitive dysfunction in AD model mice through behavioral experiments,and then clarified the role of mir-671 mediated GABA regulation on SYP in anti-AD effects of FOS through vivo and vitro experiments.These results provide a scientific basis for further revealing the pathogenesis and prevention of AD.Methods:The 5-month-old App Swe/ps1DE9 double transgenic mice were randomly divided into AD model group(AD)and AD intervention group(AD+FOS).Meanwhile,wild mice born in the same litter were randomly assigned to wild control group(WT)and wild intervention group(WT+FOS),with 5 males and 5 females in each group.Mice in AD+FOS and WT+FOS groups were fed with drinking water containing 5% FOS,and mice in WT and AD groups were fed with distilled water for6 months.At the end of the experiment,the cognitive function of each group was evaluated by water maze test.The content of GABA in brain tissue was tested by spectrophotometry.Using the q RT-PCR and Western Blot method to detect brain SYP,mir-671 expression level.Using GABA to interfere SH-SY5 Y cells treated byβ-amyloid protein(Aβ),and the expression of SYP and mi R-671 in cells were tested by q RT-PCR and Western Blotting respectively.SH-SY5 Y cells were cultured and transfected with mir-671 mimic and inhibitor.The m RNA and protein levels of SYP cells were detected by q RT-PCR and Western Blot.Results:1.The escape latency of mice in each group was shortened with the increase of training days.Compared with WT group,the escape latency of AD group was significantly longer(P <0.01);.Compared with the AD model group,the escape latency of AD intervention group was shorter(P<0.05).Compared with the wild control group,the residence time in the platform quadrant of mice in AD group was significantly shortened,and the number of cross-platform crossing was significantly decreased(P <0.01);.Compared with AD group,the times of crossing the platform and the target quadrant stay time of the AD intervention group were significant higher(P<0.05,P<0.01)..2.Compared with WT group,the expression levels of SYP m RNA and protein in brain tissue of mice.in AD group were significantly decreased(P <0.05,P <0.01).Compared with AD group,.the expression of SYP m RNA and protein in brain tissue of mice in AD intervention group.was significantly increased(P<0.05,P <0.01).3.The expression level of.mir-671 in the AD group was significantly higher than that in the WT group(P <0.01);The mir-671 in the AD intervention group was significantly lower than that in the AD group(P <0.01).4.Compared with WT group,GABA level in AD group was significantly decreased(P <0.01).The level of GABA in AD group was significantly higher than that in AD group(P <0.05).5.The expression of mir-671 of the Aβ-treated group SH-SY5 Y cells was higher than that of the control group SH-SY5 Y cells(P<0.01);The expression of mir-671 of the GABA intervention group SH-SY5 Y cells was lower than that of the Aβ-treated group SH-SY5 Y cells(P<0.01).6.The expression of SYP m RNA and protein of the mir-671mimic-transfected group SH-SY5 Y cells were lower than that of the control group SH-SY5 Y cells(P<0.01);The expression of SYP m RNA and protein of the mir-671inhibitor-transfected group SH-SY5 Y cells were higher than that of the control group SH-SY5 Y cells(P<0.01)Conclusions: FOS can improve the cognitive function of AD model mice,which may be related to the fact that it can increase the level of GABA in the brain and inhibit the expression of mir-671,and then up-regulate the expression of SYP. |
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