Background: Alzheimer’s disease (AD) is the most common neurodegenerative disorder
characterized by cognitive decline and total brain atrophy. Despite the substantial scientific effort,
the pathological mechanisms underlying neurodegeneration in AD are currently unknown. In
most studies, amyloid β peptide has been considered the key pathological change in AD. However,
numerous Aβ-targeting treatments have failed in clinical trials. This implies the need to shift the research
focus from Aβ to other pathological features of the disease.
Objective: The aim of this study was to examine the interplay between mitochondrial dysfunction,
oxidative stress and blood-brain barrier (BBB) disruption in AD pathology, using a novel approach
that involves the application of electron paramagnetic resonance (EPR) spectroscopy.
Methods: In vivo and ex vivo EPR spectroscopy using two spin probes (aminoxyl radicals) exhibiting
different cell-membrane and BBB permeability were employed to assess BBB integrity and
brain tissue redox status in the 5xFAD mouse model of AD. In vivo spin probe reduction decay
was analyzed using a two-compartment pharmacokinetic model. Furthermore, 15 K EPR spectroscopy
was employed to investigate the brain metal content.
Results: This study has revealed an altered brain redox state, BBB breakdown, as well as ROS-mediated
damage to mitochondrial iron-sulfur clusters, and up-regulation of MnSOD in the 5xFAD
Conclusion: The EPR spin probes were shown to be excellent in vivo reporters of the 5xFAD neuronal
tissue redox state, as well as the BBB integrity, indicating the importance of in vivo EPR spectroscopy
application in preclinical studies of neurodegenerative diseases.