Study on the mechanism of the regulation of Wnt/β-catenin pathway by hydroxysafflor yellow A in the protection of blood brain barrier in cerebral ischemia mice

Abstract

Objective To observe the effect of hydroxysafflor yellow A (HSYA) on the protection of blood brain barrier of cerebral ischemia mice, and explore the mechaniam. Methods Seventy-two C57/BL mice were divided into 6 groups: the sham operation group, the cerebral ischemia mice group, the TLR4 blocking group, the TLR4 blocking+ cerebral ischemia mice group, the HSYA intervention+ cerebral ischemia mice group, HSYA intervention+ TLR4 blocking+ cerebral ischemia mice group. Cerebral ischemia mice group were subjected to the middle cerebral artery occlusion (MCAO) model, TLR4 blocking was used, while TLR4 blocking was injected TLR4 antibody via right common carotid artery, and HSYA intervention group was injected 2 mg/kg HSYA by tail vein 0.5 h before cerebral ischemia. RT-PCR and western blot were applied to detect the mRNA and protein expression change of Wnt3a and β-catenin in each group. Results Compared with the cerebral ischemia mice group, the expression of TLR4 mRNA (1.63 ± 0.05, 1.53 ± 0.04, 1.84 ± 0.03 vs. 1.97 ± 0.05) significantly decreased (P<0.05 or P<0.01), the Wnt3a mRNA (0.56 ± 0.01, 0.58 ± 0.01, 0.50 ± 0.04 vs. 0.42 ± 0.03), β-catenin mRNA (0.61 ± 0.03, 0.74 ± 0.02, 0.58 ± 0.04 vs. 0.50 ± 0.03), Claudin-5 mRNA (0.54 ± 0.02, 0.58 ± 0.01, 0.47 ± 0.01 vs. 0.46 ± 0.02) mRNA significantly increased(P<0.05 or P<0.01), the protein expression of TLR4 (1.73 ± 0.05, 1.57 ± 0.03, 1.79 ± 0.08 vs. 1.89 ± 0.02) significantly decreased (P<0.05 or P<0.01), the protein expression of Wnt3a (0.67 ± 0.03, 0.74 ± 0.03, 0.57 ± 0.01 vs. 0.46 ± 0.01), Occludin (0.66 ± 0.02, 0.73 ± 0.02, 0.67 ± 0.01 vs. 0.53 ± 0.01), Claudin-5 (0.71 ± 0.01, 0.73 ± 0.01, 0.66 ± 0.01 vs. 0.64 ± 0.03) significantly increased (P<0.05 or P<0.01) in the TLR4 blocking+ cerebral ischemia mice group, the HSYA intervention+ cerebral ischemia mice group, HSYA intervention+ TLR4 blocking+ cerebral ischemia mice group. Conclusions TLR4 plays a critical regulatory role on the activation of Wnt3a and β-catenin in cerebral ischemic mice model. HSYA could intervene on the tight junction of cerebral ischemic brain through the intervention of Wnt3a and β-catenin, thus exerting the protection for cerebral ischemic brain. Key words: Hydroxysafflower yellow A; Brain ischemia; Blood-brain barrier; Wnt proteins; Mice