Sodium Tanshinone ?A Sulfonate Improves Cognitive Impairment Of APP/PS1 Transgenic Mice Through GLUT1/LRP1/A? Pathway

Background and objectiveAlzheimer's disease(AD)is a chronic and progressive neurodegenerative process characterized by intracellular and extracellular accumulation of ?-amyloid(A?)and highly phosphorylated tau fibrin.The accumulation of these aggregates will eventually lead to synaptic dysfunction and neuronal loss.The molecular mechanism of AD is not yet clear,but it is clear that it is a complex multifactorial disease.AD not only brings the physical and mental health of patients with serious harm,but also causes a huge economic burden and psychological burden to the community and the family.However,so far,there is still a lack of effective treatment which can cure AD.Therefore,to strengthen the accurate molecular mechanism of AD research,to find a lasting and effective prevention and treatment of AD drugs is of great significance.There are a variety of hypotheses about the etiology and pathogenesis of AD.The "amyloid cascade theory" has been accepted by most scholars.The theory indicated that A? abnormal metabolism caused A? abnormal increase and aggregation in the brain,triggering associated pathophysiology of AD cascade,such as oxidative stress,cells apoptosis,cholinergic system changes,tau hyperphosphorylation,synaptic dysfunction,inflammatory response induced by glial cell activation and ion homeostasis.These eventually leaded to neuronal damage and caused AD.Therefore,the theory indicated that A? was the initiation factors of AD.Tanshinone IIA is one of the main active constituents in Salvia miltiorrhiza.Many studies have shown that Tanshinone IIA has neuroprotective effect and can against free radicals,improve learning and memory ability of AD animal and protect vascular endothelial cells.But its poor water solubility and low bioavailability limit its use.Sodium tanshinone IIA sulfonate(STS)which introduced sodium sulfonate groups on the chemical structure of tanshinone IIA enhances the water solubility of the drug and improves its bioavailability and efficacy.In this study,APP/PS1 transgenic mice were used as animal model to explore the therapeutic effect of STS on AD and its possible mechanism.Methods1.Chemical experiment(1)Detection of STS to inhibit the aggregation of A? monomer by Thiof lavin T(ThT)fluorescence assay.(2)Detection of STS to promote the depolymerization of A? mature fiber by Thioflavin T(ThT)fluorescence assay.2.Animal experiment(1)STS improved the cognitive impairment of APP/PS1 transgenic mice:12-month-old male APP/PS1 transgenic mice were randomly divided into blank control group(0.99%NaCl),STS low dose group(10 mg/kg),STS high dose group(20 mg/kg).Sex-and age-matched wild mice were used as normal control group(0.9%NaCl)and negative control group(STS 20 mg/kg).10 mice in each group,intraperitoneal injection everday,a total of 2 months.Morris water maze and Y maze behavior test were used to detect the learning and memory function of mice.(2)Effect of STS on amyloid beta protein in brain of APP/PS1 transgenic mice:The amyloid plaques in the brain of APP/PS1 transgenic mice were detected by thioflavin T staining.(3)Effects of STS on A? cascade:Oxidative stress levels:ROS,malondialdehyde(MDA),superoxide dismutase(SOD);cholinergic system detection:acetylcholine transferase(ChAT),acetylcholinesterase(AChE);Western blotting was used to detect the expression of synergistic protein:PSD93,PSD95 and Synaptophysin.Western blotting was used to detect the expression of BDNF and NGF.(4)Effects of STS on the production,degradation and transportation of A?:Western blotting was used to detect the related protein of A? production,degradation and transportation:App,sApp-?,sApp-?,ADAM10,BACE1,PS1,NEP,IDE,LRP1,RAGE,GLUT1.Results1.STS could significantly reduce the fluorescence intensity of A?monomer aggregation,suggesting that STS could inhibit A? monomer to be A?fiber,that had the ability to inhibit the aggregation of A? monomer.Trend test suggested that with the increase of STS concentration,this inhibitory ability also increased.It meaned that the ability of STS to inhibit aggregation of A? monomer had a significant dose-dependent properties.2.STS could reduce the fluorescence intensity of A? that has formed fiber,suggesting that STS had the ability to promote the depolymerization of A?fibers.Trend test suggested that with the increase of STS concentration,the ability of STS to promote the depolymerization of A? fiber was stronger.It meaned that the ability of STS to promote the depolymerization of A? fiber had a significant dose-dependent properties.3.STS could improve the cognitive impairment of 12 months-APP/PS1 transgenic mice:Compared with the normal saline control of APP/PS1 mice,the mice in treatment groups performed better in the Morris water maze and Y maze test.This was reflected by significant reductions in the escape latency time and greater numbers of annulus crossing and more time spent in target quadrant in the probe trial in STS-treated mice.In spontaneous alteration tests,the mice treated with STS showed higher spontaneous alteration percentage and in novel arm exploration tests,STS-treated mice showed more time spent in the novel arm.4.STS can reduce amyloid plaques in the brain of APP/PS1 transgenic mice.5.Effect of STS on A? cascade:the level of oxidative stress was decreased,the cholinergic system was improved and the synaptic injury was repaired.6.The effect of STS on the production,degradation and transportation of A?:STS had no effect on A? production and degradation-related proteins ADAM10?BACE1?PS1?NEP?IDE,indicating that STS had no effect on the production and degradation of A?.STS could promote the expression of A?transport-related protein LRP1,and STS could promote the expression of GLUT1,suggesting that STS may promote the transport of A? from brain to blood by promoting GLUT1 expression.ConclusionIn vitro STS could inhibit the aggregation of A? monomers and promote the depolymerization of A? mature fibers in a significant dose-dependent properties.In vivo STS increased the expression of LRP1 to promote the transportation of A? from brain to blood by promoting GLUT1 expression,and then blocked the cascade of A?,and finally improved the cognitive impairment of APP/PS1 transgenic mice.