Alzheimer‐associated Aβ oligomers impact the central nervous system to induce peripheral metabolic deregulation

Abstract

Alzheimer's disease ( AD ) is associated with peripheral metabolic disorders. Clinical/epidemiological data indicate increased risk of diabetes in AD patients. Here, we show that intracerebroventricular infusion of AD ‐associated Aβ oligomers (AβOs) in mice triggered peripheral glucose intolerance, a phenomenon further verified in two transgenic mouse models of AD . Systemically injected AβOs failed to induce glucose intolerance, suggesting AβOs target brain regions involved in peripheral metabolic control. Accordingly, we show that AβOs affected hypothalamic neurons in culture, inducing eukaryotic translation initiation factor 2α phosphorylation ( eIF 2α‐P). AβOs further induced eIF 2α‐P and activated pro‐inflammatory IKK β/ NF ‐κB signaling in the hypothalamus of mice and macaques. AβOs failed to trigger peripheral glucose intolerance in tumor necrosis factor‐α ( TNF ‐α) receptor 1 knockout mice. Pharmacological inhibition of brain inflammation and endoplasmic reticulum stress prevented glucose intolerance in mice, indicating that AβOs act via a central route to affect peripheral glucose homeostasis. While the hypothalamus has been largely ignored in the AD field, our findings indicate that AβOs affect this brain region and reveal novel shared molecular mechanisms between hypothalamic dysfunction in metabolic disorders and AD. image Centrally administered Aβ oligomers can trigger insulin resistance by engaging ER stress and inflammatory signals in the central nervous system. This study provides important insights into the link between Alzheimer's disease and diabetes by pointing to a common etiology. Aβ oligomers (ΑβOs), toxins that accumulate in the AD brain and have been linked to neuronal dysfunction in brain areas related to learning and memory, impact the hypothalamus of mice and macaques, revealing a novel toxic mechanism of AβOs in the brain. Infusion of AβOs in the brain triggers peripheral glucose intolerance, insulin resistance and other diabetes‐related metabolic alterations in mice. Similar metabolic alterations were verified in two transgenic mouse models of AD . Blockade of brain inflammation or ER stress attenuates peripheral glucose intolerance induced by brain infusion of AβOs, suggesting that AβOs use a central route to disrupt metabolic control in peripheral tissues. Current results may explain why AD patients have increased risk of developing diabetes, and suggest that targeting the hypothalamus may constitute an approach to combat peripheral metabolic deregulation in AD.