Blockade of Tau Hyperphosphorylation and A|[beta]|1|[ndash]|42 Generation by the Aminotetrahydrofuran Derivative ANAVEX2-73, a Mixed Muscarinic and |[sigma]|1 Receptor Agonist, in a Nontransgenic Mouse Model of Alzheimer|[rsquo]|s Disease

摘要

The main objective of the present study was to establish whether the mixed σ1/muscarinic ligand ANAVEX2-73, shown to be neuroprotective in Alzheimer’s disease (AD) models in vivo and currently in clinical phase I/IIa, could have the ability to reduce the appearance of hyperphosphorylated Tau and amyloid-β1–42 (Aβ1–42) in the Aβ25–35 mouse model of AD. We therefore first confirmed that Aβ25–35 injection induced hyperphosphorylation of Tau protein, by showing that it rapidly decreased Akt activity and activated glycogen synthase kinase-3β (GSK-3β) in the mouse hippocampus. Second, we showed that the kinase activation, and resulting Tau alteration, directly contributed to the amyloid toxicity, as co-administration of the selective GSK-3β inhibitor 2-thio(3-iodobenzyl)-5-(1-pyridyl)-[1,3,4]-oxidiazole blocked both Tau phosphorylation and Aβ25–35-induced memory impairments. Third, we analyzed the ANAVEX2-73 effect on Tau phosphorylation and activation of the related kinase pathways (Akt and GSK-3β). And fourth, we also addressed the impact of the drug on Aβ25–35-induced Aβ1–42 seeding and observed that the compound significantly blocked the increase in Aβ1–42 and C99 levels in the hippocampus, suggesting that it may alleviate amyloid load in AD models. The comparison with PRE-084, a selective and reference σ1 receptor agonist, and xanomeline, a muscarinic ligand presenting similar profile as ANAVEX2-73 on M1 and M2 subtypes, confirmed that both muscarinic and σ1 targets are involved in the ANAVEX2-73 effects. The drug, acting synergistically on both targets, but with moderate affinity, presents a promising pharmacological profile.