The GLP-1 agonist semaglutide ameliorates cognitive regression in P301S tauopathy mice model via autophagy/ACE2/SIRT1/FOXO1-Mediated Microglia Polarization

Abstract

Tau hyper-phosphorylation has been recognized as an essential contributor to neurodegeneration in Alzheimer's disease (AD) and related tauopathies. In the last decade, tau hyper-phosphorylation has gained considerable concern in AD therapeutic development. Tauopathies are manifested with a broad spectrum of symptoms, from dementia to cognitive decline and motor impairments. Tau undergoes conformational changes and abnormal phosphorylation that mediate its detaching from microtubules, forming neurofibrillary tangles (NFTs). In the current study, a widely used P301S transgenic mice model of tauopathy was employed to evaluate the possible neuroprotective effects of semaglutide as an autophagy regulator through modifications of the brain renin-angiotensin system (RAS). Mice were divided into two groups according to their genotypes (wild type (Wt) and P301S), which were further subdivided to receive either vehicle (saline) or semaglutide (25 nmol/kg, i. p.), once every 2 days for 28 days. Current data suggest that semaglutide ameliorated the hyperactive pattern and alleviated the cognitive decline of P301S mice. It also hastened the autophagic flux through augmenting angiotensin-converting enzyme 2/sirtuin 1/forkhead box protein O1 signaling. Semaglutide also hindered the expression of phosphorylated adenosine monophosphate-activated protein kinase and phosphorylated glycogen synthase kinase-3 beta at serine 9, reducing the propagation of neuroinflammatory cytokines and oxidative reactions. Finally, semaglutide protected against hippocampal degeneration and reduced the immunoreactivity for total tau and ionized calcium-binding adapter molecule. Semaglutide showed promising neuroprotective implications in alleviating tauopathy-related AD's molecular and behavioral deficits through controlling autophagy and brain RAS.