elucidate the factors affecting the increased activity of MMP-9, we analyzed its expressional level by ELISA. As figure 3 C showed, the expressional levels of MMP-9 in the stenosis relief group increased to 46.3365.31, 61.268.65, and 62.168.11 at day 1, day 2 and day 3, respectively. However, the elevation was mitigated from day 1 to day 3 after application of ischemic postconditioning was inhibited to 35.662.21, 46.263.18, 47.562.87. These data indicated that expressional up-regulation underlies the increased activity of MMP-9 due to reestablishment of cerebral blood supply. Ischemic Postconditioning and Cerebral Edema Ischemic postconditioning suppressed quantitative reduction of claudin-5 and occludin caused by stenosis relief In this section, we tested the distribution of tight junction proteins claudin-5 and occludin on cerebral microvessels and analyzed their changes in quantity. Immuno-histochemical images showed that claudin-5 and occludin were both located sharply and continuously on cerebral microvessels in the carotid stenosis group, but they became R 115777 manufacturer discontinuous in stenosis relief group. However, ischemic postconditioning reversed partly this alteration caused by stenosis relief. For quantifying the quantitative changes of claudin-5 and occludin, ELISA assay was performed. As shown in figure 4 B and C, in comparison with those in the sham 9726632 and the carotid stenosis group, the level of claudin-5 and occludin decreased significantly from day 1 to day 3 in the stenosis relief group. 
Nevertheless, ischemic postconditioning suppressed the reduction in these two proteins at each corresponding time point. Considering claudin-5 and occludin were the constituents of BBB, we thought that the protection of ischemic postconditioning on permeability of BBB is via maintaining the quantity of claudin-5 and occludin in BBB. Discussion In this study, we found that development of brain edema and elevation of permeability of BBB following early relief of carotid stenosis were associated with increased activity and expression of MMP-9 and decreased quantity of tight junction proteins claudin5 and occludin. However, this alteration was suppressed by ischemic postconditioning. The method used in this study has been demonstrated to be effective in establishing rat model of carotid stenosis and cerebral hypoperfusion. The extent of stenosis was dependent on the diameter of the microtube bound to carotid artery. Angiography showed that a microtube with a diameter of 0.45 mm could lead to severe carotid stenosis in adult rats. Thus, as described previously, we used the microtubes to produce severe carotid stenosis and hypoperfusion in rats to imitate similar conditions in human being. It is well known that BBB plays an important role in protecting the neuronal microenvironment via restricting the movement of molecules from cerebral capillary to brain tissue. The loss of BBB integrity would lead to cerebral hemorrhage, vasogenic edema and neuronal cell death. In this study, we 8114006 evaluated the permeability of BBB by examining the content of EB and NaF within brain, as well as examined the brain water content. We found that, at the same time that water content increased following Ischemic Postconditioning and Cerebral Edema relief of carotid stenosis, BBB permeability also elevated from day 1 to day 3. This indicated that brain edema caused by stenosis relief is associated with increased BBB permeability. By contrast, both brain edema and abnormal BBB perme