Epigallocatechin-3-gallate Alleviates Cognitive Deficits in APP/PS1 Mice

Alzheimer's disease(AD)shows cognitive impairments in clinic,which is multifactorial with different etiopathogenic mechanisms such as A|3 deposition,neuroinflammation and neuronal dystrophy involved.Therefore,multi-targets drugs with neuroprotective,anti-amyloidogenic and anti-inflammatory properties will be effective in AD treatment.Epigallocatechin-3-gallate(EGCG)possesses a broad spectrum of pharmacological activities in the prevention and treatment of multiple neurodegenerative diseases.In the present study,we showed that oral administration of EGCG(50 mg/kg)for 4 months significantly attenuated the cognitive deficits in APP/PS1 transgenic mice,which served as AD model.Moreover,EGCG induced an improvement in dendritic integrity and expression levels of synaptic proteins in the brain of APP/PS 1 mice.And EGCG exerted obvious anti-inflammatory effects,which was manifested by alleviating microglia activation,decreasing pro-inflammatory cytokine(IL-β)and increasing anti-inflammatory cytokines(IL-10,IL-β).Furthermore,p-amyloid(AP)plaques were markedly reduced in the hippocampus of 6-month old APP/PS 1 mice after EGCG treatment.In conclusion,these findings indicate that EGCG improves AD-like cognitive impairments through neuroprotective,anti-amyloidogenic and anti-inflammatory effects,thus is a promising therapeutic can didate for AD.

P25/CDK5-mediated Tau Hyperphosphorylation in Both Ipsilateral and Contralateral Cerebra Contributes to Cognitive Deficits in Post-stroke Mice

Objective Post-stroke cognitive impairment(PSCI)develops in approximately one-third of stroke survivors and is associated with ingravescence.Nonetheless,the biochemical mechanisms underlying PSCI remain unclear.The study aimed to establish an ischemic mouse model by means of transient unilateral middle cerebral artery occlusions(MCAOs)and to explore the biochemical mechanisms of p25/cyclin-dependent kinase 5(CDK5)-mediated tau hyperphosphorylation on the PSCI behavior.Methods Cognitive behavior was investigated,followed by the detection of tau hyperphosphorylation,mobilization,activation of kinases and/or inhibition of phosphatases in the lateral and contralateral cerebrum of mice following ischemia in MACO mice.Finally,we treated HEK293/tau cells with oxygen-glucose deprivation(OGD)and a CDK5 inhibitor(Roscovitine)or a GSK3βinhibitor(LiCl)to the roles of CDK5 and GSK3βin mediating ischemia-reperfusion-induced tau phosphorylation.Results Ischemia induced cognitive impairments within 2 months,as well as causing tau hyperphosphorylation and its localization to neuronal somata in both ipsilateral and contralateral cerebra.Furthermore,p25 that promotes CDK5 hyperactivation had significantly higher expression in the mice with MCAO than in the shamoperation(control)group,while the expression levels of protein phosphatase 2(PP2A)and the phosphorylation level at Tyr307 were comparable between the two groups.In addition,the CDK5 inhibitor rescued tau from hyperphosphorylation induced by OGD.Conclusion These findings demonstrate that upregulation of CDK5 mediates tau hyperphosphorylation and localization in both ipsilateral and contralateral cerebra,contributing to the pathogenesis of PSCI.