| Background: Brain edema is one of the complications associated with cerebral ischemia. Ischemic brain edema and resultant increase in intracranial pressure will lead to death within the first week of an ischemic stroke. Two primary types of brain edema can be distinguished, cytotoxic (cellular) and vasogenic. In vasogenic edema formation, the mechanism is disruption of the blood-brain barrier (BBB). The time course of edema and the BBB breakdown and the relationship between edema formation and opening of the BBB after brain ischemia are still controversial. There is no detail research about the time course of brain edema formation and the BBB opening and the relationship between them after permanent focal cerebral ischemia in mice.Many methods are used to evaluate ischemic brain edema, including: (1) a dry/wet weight method to measure brain water content; (2) measurement of brain tissue specific gravity; (3) imaging analysis for brain slice to calculate brain volume in vitro; (4) brain imaging for patients or animals in vivo. The methods for assessing disruption of the BBB include uses of endogenous or exogenous tracers that labeled by isotope, enzyme, fluorescence substances, paramagnetic metal complex; the tracers are measured with gamma counter, fluorescence spectrophotometer or fluorescencemicroscope, light microscope or electron microscope, magnetic resonance imaging (MRI) for qualitative and quantitative detecting disruption of the BBB. Though there are various' methods, their sensitivities are different, and these methods are not suitable for repeated use of a same sample except MRI.Objectives: To resolve these problems in measurement of brain edema and BBB disruption, we aimed to develop a simple computer-assisted method of photomacrograph on brain surface. This method was used to measure brain edema and BBB disruption in comparison with typical methods. Based on the methodology, we observed the time course of brain edema and BBB disruption in mice after permanent focal cerebral ischemia in order to clarify the properties of their development and provide the evidence for consideration of therapeutic windows of anti-stroke drugs.Methods: Permanent focal cerebral ischemia was induced by middle cerebral artery occlusion (MCAO) in mice, and the development of brain edema and BBB disruption within 24 h after ischemia were determined by a series of methods. According to a recently developed photomacrography, we used a digital camera to photograph the surface of whole brains without any pre-preparation procedures. Then we analyzed the images quantitatively by a computer-assisted system, and the increase percentage of brain surface area in ischemic hemisphere was calculated. Furthermore, we analyzed the hemorrhage and traced Evans blue on the brain surface semi-quantitatively. Typical image analysis of brain slices, brain wet/dry weight measurement, and Evans blue extravasation were also used simultaneously to verify the feasibility of this method.Results: The increase percentage of the brain area measured by photomacrography became significant at 1 h after ischemia, as sensitive as the measurement of brain water content. However, significant increase was found after ischemia by image analysis of brain slices at 3 h, while Evans blue extravasation was rapidly measured by detecting fluorescence at 0.5 h. These changes lasted and gradually became more severe within 24 h after ischemia. These results indicated that BBB opened earlier from 0.5 h, and brain edema occurred from 1 h after focalischemia; they developed within 24 h after ischemia time-dependently. The measurement of brain edema by photomacrography on brain surface had the same sensitivity as that of brain water content. The variables measured by photomacrography closely related to those of behavior assessment, brain water content and infarct volume. On the other hand, the hemorrhage and traced Evans blue observed on brain surface occurred at 6 h after ischemia, but showed a similar pattern of time-course as other methods. Conclusions...
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