Effects of hyperbaric oxygen on the occludin in the brain tissues and permeability of blood brain barrier after cerebral ischemia-reperfusion in mice

Abstract

Objective To investigate effects of hyperbaric oxygen (HBO) on the occludin and ZO-1 in the brain tissues and permeability of blood brain barrier (BBB) after cerebral ischemia-reperfusion in mice. Methods Male Wistar mice were randomly divided into 4 groups; the sham group, the ischemia-reperfusion group (IR) , the HBO group and the IR + HBO group. Following development of the cerebral ischemia reperfusion model, 5 sessions of HBO at 0.25 Mpa were applied during the reperfusion period, and 2% Evens blue (EB) was injected into the tail veins an hour before the animals were executed. Following ischemia reperfusion, changes in the permeability of BBB were monitored with the EB method. Following ischemia reperfusion, the distributions of occludin and ZO-1 in the brain tissue were observed with immunohistochemical method, and the expressions of occludin, ZO-1, and the contents of EB were determined by Western Blot and spectrophotometer. Results When compared with that of the sham group, the levels of EB in the brain tissue for the IR group increased significantly, reaching peak at 4 h following IR injury (P＜0. 01). In the IR + HBO group, EB contents in the brain tissue decreased significantly, when compared with those of the IR group ( P＜ 0.01). However, no significant changes in the expression of occludin, ZO-1 and the content of EB in the brain tissue could be noted in the HBO, when compared with those of the sham group (P＞0.05). In the IR group, the expressions of occludin and ZO-1 at 4, 12, 24, 48, 72 h after reperfusion decreased significantly, when compared with those at 0 h( P＜0. 01). However, for the IR + HBO group, the expressions of occludin and ZO-1 at 72 h after reperfusion increased markedly (P＜0. 01). No obvious changes in the expression of occludin and ZO-1 could be noted in the brain tissue in the animals in the HBO group, when compared with those in the sham group (P＞0. 05). Conclusions HBO intervention could increase markedly the expressions of occludin and ZO-1 in the ischemia-reperfusion brain tissue, thus decreasing permeability of BBB. Key words: Hyperbaric oxygen; Blood brain barrier; Ischemia reperfusion; Occludin; ZO-1; Rat