Alzheimer risk factors age and female sex induce cortical Aβ aggregation by raising extracellular zinc.
Zsolt DatkiZita Galik-OlahEmese Janosi-MozesViktor SzegediJános KálmánÁkos Gábor HunyaLivia FulopHaruna TamanoAtsushi TakedaPaul A AdlardAshley I BushPublished in: Molecular psychiatry (2020)
Aging and female sex are the major risk factors for Alzheimer's disease and its associated brain amyloid-β (Aβ) neuropathology, but the mechanisms mediating these risk factors remain uncertain. Evidence indicates that Aβ aggregation by Zn2+ released from glutamatergic neurons contributes to amyloid neuropathology, so we tested whether aging and sex adversely influences this neurophysiology. Using acute hippocampal slices, we found that extracellular Zn2+-elevation induced by high K+ stimulation was significantly greater with older (65 weeks vs 10 weeks old) rats, and was exaggerated in females. This was driven by slower reuptake of extracellular Zn2+, which could be recapitulated by mitochondrial intoxication. Zn2+:Aβ aggregates were toxic to the slices, but Aβ alone was not. Accordingly, high K+ caused synthetic human Aβ added to the slices to form soluble oligomers as detected by bis-ANS, attaching to neurons and inducing toxicity, with older slices being more vulnerable. Age-dependent energy failure impairing Zn2+ reuptake, and a higher maximal capacity for Zn2+ release by females, could contribute to age and sex being major risk factors for Alzheimer's disease.