Quantitative evaluation of Blood Brain Barrier permeability in transient focal cerebral ischemia in the rat

Introduction: Development of brain edema following focal cerebral ischemia exacerbates primary ischemic injury. Blood brain barrier (BBB) opening is an important part of edema named as vasogenic brain edema. In this study, quantitative alterations of BBB permeability is experimentally evaluated using transient focal cerebral ischemia in the rat. Methods: Two groups of male rats (ischemic and sham) were anesthetized with chloral hydrate. In the ischemic group, middle cerebral artery (MCA) was occluded for 60 minutes using intraluminal filament method followed by reperfusion, whereas, in the sham group the same procedure, except MCA occlusion, was used. An IV injection of Evans blue (EB) was done 30 minutes after surgery. After 24 hours of reperfusion the neurological deficit score (NDS) was evaluated with a standard test. Then the animal was killed, the brain excised and prepared for quantitative evaluation of BBB permeability by detection of Evans blue (EB) extravasation. Results: The mean of NDS in sham and ischemic groups were 1 and 2.25±0.31 respectively, indicating severe motor disabilities due to cerebral ischemia. In the ischemic group the concentration of EB in the right hemisphere (ischemic) was 12.48±1.94µg/g which was significantly higher than of the left hemisphere (non ischemic 1.44±0.39µg/g) or both hemispheres of the sham group. Furthermore, a direct correlation seems to exist between NDS and EB concentration in both groups. Conclusion: This study is indicating that quantitative detection of Evans blue extravasation technique is capable of measuring the alterations of BBB permeability in cerebral ischemia in the rat.