Detection of Blood-brain barrier disruption in a mouse model of transient cerebral ischemia by EPR imaging

INTRODUCTION EPR imaging using nitroxides is a powerful non-invasive method for visualizing the redox status modulated by oxidative stress in vivo. Recently we successfully reduced the scan time of three-dimensional (3D) EPR imaging of nitroxides in rodents. This system enables us to obtain 3D images of nitroxide probes with a half-life of a few minutes in living mice [1]. Another advantage of using the rapid field-scanning system is that, compared with other EPR imaging systems, we can collect a greater number of projections, before the signal becomes undetectable. The benefit of which is to obtain a better quality of reproduction for the resulting EPR images. In this study, using the improved EPR imaging system we assessed the redox status of an ischemia-reperfusion (IR) model mouse brain, as well as the effect of oxidative stress on its infarcted hemisphere. The results obtained in this study clearly show that through the use of blood-brain barrier (BBB)-permeable and BBB-impermeable nitroxides, rapid field scanning EPR imaging can be used to asses BBB permeability and time course of changes in the BBB-permeability of the wounded hemisphere of IR model mice. The infarcted hemisphere was visualized by three-dimensional surface-rendered EPR images.