Vulnerability of primary neurons derived from Tg2576 Alzheimer mice to oxygen and glucose deprivation: role of intraneuronal amyloid-β accumulation and astrocytes.

Vito Antonio Baldassarro,Alessandra Marchesini,Luciana Giardino,Laura Calzà

doi:10.1242/dmm.028001

Vito Antonio Baldassarro, Alessandra Marchesini + Show 2 more

Open Access

https://doi.org/10.1242/dmm.028001

Copy DOI

Abstract

ABSTRACTMicrovascular dysfunction is considered an integral part of Alzheimer disease (AD) pathogenesis, but the possible relationship between amyloid pathology, microvascular dysfunction and cell death is still unclear. In order to investigate the influence of intraneuronal amyloid-β (Aβ) accumulation on vulnerability to hypoxia, we isolated primary cortical neurons from Tg2576 (carrying the amyloid precursor protein APPSwe mutation) and wild-type fetal mice. We first demonstrated that neurons isolated from Tg2576 newborn mice show an increase in VEGFa mRNA expression and a decrease in the expression of the two VEGF receptors, Flt1 and Kdr, compared with wild-type cells. Moreover, APPSwe primary neurons displayed higher spontaneous and glutamate-induced cell death. We then deprived the cultures of oxygen and glucose (OGD) as an in vitro model of hypoxia. After OGD, APPSwe neurons display higher levels of cell death in terms of percentage of pyknotic/fragmented nuclei and mitochondrial depolarization, accompanied by an increase in the intraneuronal Aβ content. To explore the influence of intraneuronal Aβ peptide accumulation, we used the γ-secretase inhibitor LY450139, which showed that the reduction of the intracellular amyloid fully protects APPSwe neurons from OGD-induced degeneration. Conditioned medium from OGD-exposed APPSwe or wild-type astrocytes protected APPswe neurons but not wild-type neurons, during OGD. In conclusion, the presence of the mutated human APP gene, leading to the intracellular accumulation of APP and Aβ fragments, worsens OGD toxicity. Protection of APPSwe neurons can be obtained either using a γ-secretase inhibitor or astrocyte conditioned medium.

Highlights

IntroductionThe fine regulation of the blood support to the neurons is performed by the cerebrovascular unit (CVU) which provides the functional coupling between energy demand and vasodilation (Nelson et al, 2016)
There is a lack of studies aimed at examine the inter-related role of intracellular amyloid precursor protein (APP)/Aβ peptide accumulation and neurovascular coupling during Alzheimer disease (AD) development and/or progression (Sagare et al, 2012)
Cell-based high-throughput technology combining cellular imaging with high-throughput data analysis (Radio and Mundy, 2008) has been successfully applied to drug screening (O’Brien, 2014)

Summary

Introduction

The fine regulation of the blood support to the neurons is performed by the cerebrovascular unit (CVU) which provides the functional coupling between energy demand and vasodilation (Nelson et al, 2016). This histological structure includes neurons, vascular cells (endothelial cells, pericytes and vascular smooth muscle cells), glial cells (astrocytes, microglia, and oligodendrocytes) and extracellular matrix protein, which plays a part in blood–brain barrier (BBB) regulation. In the CVU, astrocytes define functional domains and contact the microvessels with endfeet plastered on the vessel wall (Nedergaard et al, 2003). This physical contact is used to guarantee the lactate/glucose dynamic in the CVU (Barros et al, 2007)

Objectives

Methods

Results

Conclusion