Effects And Mechanisms Of Diallyl Disulfide On AQP4 Polarity Distribution In Brain Tissue Of AD Model Mice

Objective: Alzheimer's disease is an irreversible,progressive neurodegenerative disorder,with progressive memory impairment as the first symptom.At present,the exception accumulation of A? in brain is thought to play a critical role in AD pathogenesis.Therefore,reducing the deposition of A? is essential for the prevention and treatment of AD.It has been reported that abnormal mechanisms of A? clearance is an important reason for A? accumulation in late-onset AD brain.Animal studies found that about 75%of extracellular A? is cleared by the blood–brain barrier,with only about 10% being cleared by interstitial fluid bulk flow.However,recent studies have indicated that interstitial fluid bulk flow contributes to a larger portion of extracellular A? clearance than previously thought.Aquaporin-4 dependent glymphatic pathway has been demonstrated to play an important role in driving the removal of soluble A? from the interstitium.AQP4 is the most highly expressed aquaporin in the mammalian brain,with the polarized distribution in the perivascular endfeet of astrocytes.Several lines of evidence has shown that AQP4 mislocalization performs a crucial role in the reduction of A? clearance.M1/M23-AQP4 ratio was found to be elevated with the increase of total AQP4 protein expression after hypoglycemia which may cause disorganization of the OAPs and loss of AQP4 polarity.In addition,SNTA1 also can regulate the polarity distribution of AQP4.SNTA1 was found to be regulated by histone deacetylase1(HDAC1).Diallyl disulfide(DADS)is the main active ingredient in garlic,which has antineuritic activity,inhibit HDAC1,and can reduce soluble and fibrilair A? in the T92576 transgenic mouse brain and thereby decrease the numbers of senile plaques,but the exact mechanism is unknown.Whether DADS can reduce A? deposition by affecting the distribution of AQP4 polarity in AD model mice has not been reported.Through using APPswe/PSldE9 double transgenic gene model mice,we investigated the the distribution of AQP4 polarity in AD model mice,and the changes of SNTA1 mRNA and protein expression and and the level of histone acetylation in the brain in order to reveal its mechanism for providing a theoretical basis for prevention and treatment of AD.Methods:According to the body weight,20 healthy APPswe/PSldE9 doubletransgenicpositive mice were randomly divided into two groups(AD model and AD intervention,n=10);20 healthy wild C57BL/6J mice with the nest were randomly divided into two groups(wild control and wild intervention,n=10).Mice in the AD intervention and wild intervention groups were treated with 50 mg/Kg DADS dissolved in edible oil by a single oral gavage daily.Mice in the AD model and wild control groups were given equivalent edible oil.1.AQP4 polarity distribution in mice brain tissue were detected by Immunofluorescence staining.2.The total RNA cortex of cerebra was extracted,and the relative levels of AQP4,M1,M23-AQP4,SNTA1 and HDAC1 mRNA expression in the cerebral cortex of mice were analysed by quantitative reverse transcriptase-polymerase chain reaction using ?-actin as an intemal reference.3.The total protein of cortex of cerebra was extracted,and the levels of AQP4,M1,M23-AQP4,SNTA1,Ace-H3K9,Ace-H4K12,and HDAC1 protein expression in the cerebral cortex of mice were measured by Western blot with using ?-actin as an intemal reference.Results:1.Immunoflorescent labeling demonstrated that AQP4 expression was highly localized to astrocytic endfeet,showing a polar distribution,in the cerebral cortex of wild control mice.In the cerebral cortex of AD mice,AQP4 localization was severely perturbed,exhibiting a loss of polarity to the astrocytic endfeet and an increase of somal labeling.After DADS intervention,the polarity of AQP4 was recovered in APP/PS1 mice brains.2.Higher levels of AQP4,M1-AQP4 mRNA and protein were found in the cerebral cortex of AD model and AD intervention groups compared with wild control group(P<0.01).Compared with AD model group,higher level were found in the cerebral cortex of AD intervention groups(P<0.01).Compared with wild control group,the levels of M23-AQP4 mRNA and protein were increased remarkably found in the cerebral cortex of AD intervention groups(P<0.01).Higher levels of M1\M23-AQP4 were found in the cerebral cortex of AD model and AD intervention groups compared with wild control group(P<0.01).Compared with wild control group,the levels of SNTA1 mRNA and protein were decreased remarkably found in the cerebral cortex of AD model groups(P<0.01).Compared with AD model group,higher level were found in the cerebral cortex of AD intervention groups(P<0.01).3.Lower levels of Ace-H3K9 and Ace-H4K12 protein were found in the cerebral cortex of AD model and AD intervention groups compared with wild control group(P<0.01).Compared with AD model group,higher level were found in the cerebral cortex of AD intervention groups(P<0.01).Compared with wild control group,the levels of HDAC1 mRNA and protein were increased remarkably found in the cerebral cortex of AD model groups(P<0.01).Compared with AD model group,lower level were found in the cerebral cortex of AD intervention groups(P<0.01).Conclusion: 1.The polarity distribution of AQP4 in brain of AD mice is disordered,which can be recovered by DADS.2.The level of M1,M23-AQP4 ratio in cerebral codex is increased,and SNTA1 expression level is decreased in AD model mice.DADS can alleviate the decrease of SNTA1 expression,but has no effect on the level of M1,M23-AQP4 ratio in cerebral cortex of AD mice.3.The levels of Ace-H3K9 and Ace-H4K12 are decreased and the expression of HDAC1 is increased in cerebral codex of AD mice,which can be ameliorated by DADS.