6533b7d8fe1ef96bd126ad60

RESEARCH PRODUCT

Insulin resistance as common molecular denominator linking obesity to Alzheimer’s disease

Pasquale PiconeLuca CaruanaAntonella Marino GammazzaFlavia MulèElisa MessinaDomenico NuzzoSara BaldassanoMarta Di CarloFrancesco Cappello

subject

Malemedicine.medical_specialtyTime FactorsAdipokineAmyloidogenic ProteinsInflammationBiologyDiet High-Fatmedicine.disease_causeAdipokines Alzheimer’s disease gene expression inflammation insulin resistance mitochondrial dysfunction obesity.Settore BIO/09 - FisiologiaGlycogen Synthase Kinase 3MiceInsulin resistanceAlzheimer DiseaseInternal medicinemedicineAnimalsInsulinObesityReceptorGSK3BGlycogen Synthase Kinase 3 betaSettore BIO/16 - Anatomia UmanaNeurodegenerationBrainmedicine.diseaseReceptor InsulinMice Inbred C57BLDisease Models AnimalOxidative StressInsulin receptorEndocrinologyGene Expression RegulationNeurologyCase-Control Studiesbiology.proteinCytokinesNeurology (clinical)Amyloid Precursor Protein SecretasesInsulin Resistancemedicine.symptomOxidative stressSignal Transduction

description

Alzheimer’s disease (AD) is an aging-related multi-factorial disorder to which metabolic factors contribute at what has canonically been considered a centrally mediated process. Although the exact underlying mechanisms are still unknown, obesity is recognized as a risk factor for AD and the condition of insulin resistance seems to be the link between the two pathologies. Using mice with high fat diet (HFD) obesity we dissected the molecular mechanisms shared by the two disorders. Brains of HFD fed mice showed elevated levels of APP and Aβ 40 /Aβ 42 together with BACE, GSK3β and Tau proteins involved in APP processing and Aβ accumulation. Immunofluorescence, Thioflavin T staining experiments, confirmed increased Aβ generation, deposition in insoluble fraction and plaques formation in both the hippocampus and the cerebral cortex of HFD mice. Presence of Aβ 40 /Aβ 42 in the insoluble fraction was also shown by ELISA assay. Brain insulin resistance was demonstrated by reduced presence of insulin receptor (IRs) and defects in Akt-Foxo3a insulin signaling. We found reduced levels of phospho-Akt and increased levels of Foxo3a in the nuclei of neurons where proapototic genes were activated. Dysregulation of different genes related to insulin resistance, especially those involved in inflammation and adipocytokines synthesis were analyzed by Profiler PCR array. Further, HFD induced oxidative stress, mitochondrial dysfunction and dynamics as demonstrated by expression of biomarkers involved in these processes. Here, we provide evidence that obesity and AD markers besides insulin resistance are associated with inflammation, adipokine dyshomeostasis, oxidative stress and mitochondrial dysfunction, all mechanisms leading to neurodegeneration.

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