Protective Effects And Mechanisms Of Baicalein On Aβ_25-35-induced Injury In PC12 Cells

Rationales : Alzheimer’s disease（AD）is a relatively common neurodegenerative disease.However,there is no ideal drug that can prevent and improve AD until so far.Baicalein is a flavonoid isolated from the roots of Scutellaria baicalensis Georgi.Our previous study has found that baicalein could not only prolong the lifespan of Drosophila melangaster,but also improve the cognitive impairment of D-galactose-induced aging rats and SAMP8 mice.However,the protective effects and possible mechanisms of baicalein on Aβ_25-35-induced PC12 cytotoxicity are unclear.Objective : The main purpose of this article is to investigate the inhibitory effect of baicalein on Aβ_25-35 aggregation and the protective effect of baicalein on Aβ_25-35-injured PC12 cells,and also explore the neuroprotective mechanisms of baicalein based on JAK2/STAT1 pathway and metabolomics approach.Methods:1.The inhibitory effect of baicalein on Aβ_25-35 aggregation was detected by using Th-T fluorescence experiment;2.The protective effects of baicalein on Aβ_25-35-injured PC12 cells were evaluated by measure of cell viability,LDH release rate,apoptosis rate,NO,IL-8,ROS,MMP,ATP and mitochondrial complex I;3.The effects of baicalein on protein expression in JAK2/STAT1 pathway were investigated by Western blot in Aβ_25-35-injured PC12 cells;4.The metabolites regulated by baicalein in Aβ_25-35-injured PC12 cells were obtained by LC-MS/MS metabolomics approach.Results:1.Th-T fluorescence experiments showed that baicalein could not only inhibit the aggregation of Aβ_25-35,but also depolymerize the pre-formed Aβ_25-35 aggregated fibers;2.Baicalein could improve the survival of PC12 cells injured by Aβ_25-35.The mechanisms may be related to inhibiting apoptosis,reducing the release of LDH,NO and IL-8,inhibiting ROS production and increasing the levels of MMP,ATP and mitochondrial complex I;3.The results from Western bolt showed that baicalein could inhibit the phosphorylation of JAK2 and STAT1,and the expression of i NOS and COX-2;4.LC-MS/MS metabolomics analysis showed that 6 differential metabolites were detected in Aβ_25-35 group as compared with control group.Baicalein could reversely regulate 5 differential metabolites,including Larginine,proline,Creatine,4-guanidinobutyric acid and niacin,implicated in 2 metabolic pathways,including nicotinate and nicotinamide metabolism,arginine and proline metabolism.Conclusion: Baicalein could protect against Aβ_25-35-induced cytotoxicity in PC12 cells,and the mechanisms were closely related to the inhibition of aggregation,reduction of apoptosis,inhibition of JAK2/STAT1 signaling pathway,regulation of arginine and proline metabolism;nicotinic acid and nicotinamide metabolism.