In Vivo/Ex Vivo EPR Investigation of the Brain Redox Status and Blood-Brain Barrier Integrity in the 5xFAD Mouse Model of Alzheimer's Disease

Abstract

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 re- search 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. Method: In vivo and ex vivo EPR spectroscopy using two spin probes (aminoxyl radicals) exhibit- ing 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 spectros- copy was employed to investigate the brain metal content. Results: This study has revealed an altered brain redox state, BBB breakdown, as well as ROS-me- diated damage to mitochondrial iron-sulfur clusters, and up-regulation of MnSOD in the 5xFAD model. Conclusion: The EPR spin probes were shown to be excellent in vivo reporters of the 5xFAD neu- ronal tissue redox state, as well as the BBB integrity, indicating the importance of in vivo EPR spec- troscopy application in preclinical studies of neurodegenerative diseases.

Bridging the buzz: In vivo EPR imaging unlocking the secrets of honey bee health

“…For the 2D EPR imaging experiment, honey bees were fed with a 400 mM solution of redox-sensitive membrane-permeable aminoxyl spin-probe 3-carbamoyl PROXYL (3CP) dissolved in Acacia honey in a 1/4 volume ratio. This spin probe is non-toxic and is commonly employed in in vivo studies of small animals [25]. The quantity of this mixture provided to each honey bee was equivalent to 10% of its body mass.…”

Redox signaling and metabolism in Alzheimer's disease

“…Monitoring the redox state in vivo requires specific biocompatible probes for different reactive species and, since their transient concentrations are usually very low, high sensitivity. Specific electron paramagnetic resonance (EPR) probes (aminoacyl radicals) are in vivo reporters to analyze the redox state of the brain and the blood-brain barrier integrity in a 5xFAD mouse model of AD (Vesković et al, 2021 ). A near-infrared emissive iridium probe is sensitive and selective toward peroxynitrite/glutathione redox cycles (Wu et al, 2021 ).…”

The Effect of a Magnetic Field on the Transport of Functionalized Magnetite Nanoparticles into Yeast Cells

“…If the resonance condition is met and an appropriate quantum of radiation with energy corresponding to the energy difference between these levels is supplied to the system, the ESR phenomenon will be registered as the first derivative of the absorption signal [19][20][21]. It has been successfully applied in various studies, including those investigating the properties of magnetic nanoparticles [22][23][24][25][26][27], iron complexes and free radicals in blood and tissues [28][29][30][31][32][33][34][35], as well as geological and archaeological materials [36][37][38][39]. ESR studies confirm the penetration of nanoparticles into cells and facilitate monitoring of this whole process.…”