CLDN5 and ischemia: In the present study, we found that the claudin-5 mRNA levels in the rats in the I/R group were significantly lower than those of the rats in the Sham group at 72 h after ischemia; moreover, claudin-5 protein expression was downregulated from 48 h after the ischemic insult, and the decrease in claudin-5 protein expression was most evident at 72 h.