Effects And Mechanisms Of Baicalein On Learning And Memory Impairment In SAMP8 Mice

Rationales: Aging is a complex physiological process in which various organs gradually decline.Brain is particularly sensitive in the process of aging,mainly characterized by the decline of learning and memory abilities,which jeopardizes the physical and mental health of the elderly.However,there is no ideal drug that can prevent or improve the deficits in aging learning and memory.Baicalein is a flavonoid isolated from the roots of Scutellariae baicalensis Georgi.Our previous study has found that baicalein can not only prolong the lifespan of Drosophila by inhibiting oxidative stress,but also improve the cognitive impairment of D-galactose-induced aging rats by inhibiting inflammation and regulating metabolic function.However,the mechanisms of baicalein in improving cognitive impairment remain elusive.Objective: The aims of this study are to verify the effects of baicalein on aging learning and memory impairment in the senescence-accelerated mouse prone 8(SAMP8);to explore the effects of baicalein on intestinal microbiome and whether this effct is related with its cognition ameliorating effect;to reveal the key genes and pathways in the brain cortex regulated by baicalein,that explaining the molecular mechanisms of baicalein in improving learning and memory impairment in SAMP8 mice.Methods: 1.The grading score of senescence,novel object recognition test,olfactory memory test,Morris water maze test and nest building test were applied to verify the success of SAMP8 mice model,and to clarify the effects of baicalein(200 mg/kg)in improving senescence status and learning and memory impairment of SAMP8 mice.2.The intestinal microbial community analysis was carried out by 16 S r RNA sequencing technology;the levels of proinflammatory cytokines in cortex were detected by ELISA kits;correlation analysis revealed a new way that baicalein improves aging cognitive impairment through regulating intestinal flora.3.The key genes and pathways affected by baicalein for learning and memory improvement effect in SAMP8 mice were deciphered by integration of RNA-sequencing and network pharmacology.Furthermore,the genes and associated proteins in key pathway were verified by q RT-PCR and Western blot.Results: 1.Eight-month-old SAMP8 mice have showed significant aging accompanied by learning and memory impairment,indicating the model is successful.The senescence status and learning and memory impairment of SAMP8 mice were significantly ameliorated with administration of baicalein(200 mg/kg)for 8 weeks.2.Baicalein altered the β diversity of intestinal microbiome,inhibited five inflammation-related strains,protected one strain associated with longevity,and decreased the cortical levels of IL-1β,IL-6,and TNF-α in SAMP8 mice.Correlation analysis revealed that the abundances of four strains(Mucispirillum,Bacteroides,Sutterella,and Christensenellaceae)were correlated with cognitive abilities or the levels of proinflammatory cytokines.3.The RNA-seq results showed that 1035 differentially expressed genes(DEGs)were found in 10-month-old SAMP8 mice versus the age-matched SAMR1 mice.Treatment with baicalein for eight weeks altered 654 DEGs in the SAMP8 mice,214 DEGs,among them,could be reversely regulated by baicalein.Fifty hub DEGs and eight signaling pathways including Cytokinecytokine receptor interaction,Jak/STAT signaling pathway,PI3K/Akt signaling pathway,Neuroactive ligand-receptor interaction,Chemokine signaling pathway were acquired through network pharmacology analysis.The hub genes and related proteins in Jak-STAT signaling pathway were verified by q RT-PCR and Western blot,suggesting the role of baicalein on improving learning and memory impairment in SAMP8 mice is dependent upon the inhibition of Aβ and RAGE/Jak2/STAT1 cascade.Conclusion: Baicalein can significantly improve learning and memory impairment in SAMP8 mice,which is closely related to regulation of intestinal microbiome,inhibition of cortical proinflammatory cytokines,and inhibition of Aβ and RAGE/Jak2/STAT1 cascade.