Fig. 8: DDAH-1^−/− rats showed decreased expressions of tight junction proteins.

a Representative western blots of ZO-1, occludin, and claudin-5. b–d Statistic analysis and quantification respectively. Under normal condition, the expression of ZO-1, occludin and claudin-5 significantly decreased in DDAH-1^−/− rats compared to WT rats (n = 5, p < 0.001). After ARG supplementation, the expression of ZO-1, occludin and claudin-5 significantly increased (n = 5, p < 0.001). Under ischemic conditions, the expression of tight junction proteins in both WT and KO rats decreased (n = 5, p < 0.001), and the expression in KO rats was significantly lower than WT rats (n = 5, p < 0.001). Also, the ARG supplement increased the expression of tight junction proteins both in KO and WT rats (n = 5, p < 0.001). e Statistic analysis and quantification of mRNA levels respectively. The mRNA levels of TJ proteins (normalized to SHAM group) showed no significant difference in these groups (n = 5, p > 0.05). Data are presented as mean ± SD. ^nsp > 0.05, *p < 0.05, ***p < 0.001. KO knockout, WT wild-type, ARG L-arginine, MCAO/R middle cerebral artery occlusion/reperfusion, DDAH-1 dimethylarginine dimethylamino hydrolase-1, ZO-1 zonula occludens 1.