Increase in P-glycoprotein levels in the blood-brain barrier of partial portal vein ligation /chronic hyperammonemia rats is medicated by ammonia/reactive oxygen species/ERK1/2 activation: In vitro and in vivo studies
Increase in P-glycoprotein levels in the blood-brain barrier of partial portal vein ligation /chronic hyperammonemia rats is medicated by ammonia/reactive oxygen species/ERK1/2 activation: In vitro and in vivo studies
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氨/活性氧/ERK1/2 激活可提高部分门静脉结扎/慢性高氨血症大鼠血脑屏障中 P-糖蛋白水平：体外和体内研究
DOI：
10.1016/j.ejphar.2019.01.005
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发表时间：
2019
影响因子：
5
通讯作者：
Liu Li
中科院分区：
文献类型：
--
作者：
Zhou Yaqian;Zhou Junjie;Li Ping;Xie Qiushi;Sun Binbin;Li Ying;Chen Yang;Zhao Kaijing;Yang Tingting;Zhu Liang;Xu Jiong;Liu Xiaodong;Liu Li
肝功能衰竭改变p -糖蛋白（P-gp）功能和血脑屏障（BBB）表达，部分原因是高氨血症。本研究旨在探讨部分门静脉结扎术（PVL）加慢性高氨血症（CHA）对大鼠血脑屏障P-gp功能和表达的影响。实验大鼠分为假手术大鼠、PVL大鼠、CHA大鼠和PVL+CHA大鼠。PVL+CHA大鼠术后用含氨饲料饲养2周。测定罗丹明123和荧光素钠的脑血浆浓度比（Kp）和表观单向内流常数（Kin），分别评估P-gp和血脑屏障完整性的功能。采用人大脑微血管内皮细胞（HCMEC/D3）评价氨对P-gp表达及功能的影响。PVL+CHA可显著降低罗丹明123的激酶和激酶，但不影响荧光素在脑内的分布。CHA和PVL +CHA大鼠皮层和海马膜蛋白P-gp表达显著升高，PVL +CHA大鼠尤为明显，而磷酸化ERK1/2仅在PVL +CHA大鼠中显著升高。大鼠脑内紧密连接蛋白claudin-5和occluding的表达保持不变。体外实验结果显示，NH4Cl增加了HCMEC/D3中活性氧、P-gp的膜表达和功能以及磷酸化的ERK1/2水平。nh4cl诱导的改变被活性氧清除剂n -乙酰半胱氨酸和ERK1/2抑制剂U0126逆转。综上所述，PVL+CHA在一定程度上通过氨促进了大鼠血脑屏障P-gp的功能和膜转运。活性氧/ERK1/2通路激活可能是氨上调血脑屏障P-gp表达和功能的原因之一。
Liver failure altered P-glycoprotein (P-gp) function and expression at blood-brain barrier (BBB), partly owing to hyperammonemia. We aimed to examine the effects of partial portal vein ligation (PVL) plus chronic hyperammonemia (CHA) on P-gp function and expression at rat BBB. Experimental rats included sham-operation (SH), PVL, CHA and PVL+CHA. The PVL+CHA rats were developed by ammonia-containing diet for 2 weeks after operation. The brain-to-plasma concentration ratios (Kp) and apparent unidirectional influx constants (Kin) of rhodamine123 and sodium fluorescein were measured to assess function of P-gp and BBB integrity, respectively. Human cerebral microvascular endothelial cells (HCMEC/D3) were used to assess effects of ammonia on P-gp expression and function. It was found that PVL+CHA significantly decreased Kpand Kinof rhodamine123 without affecting brain distribution of fluorescein. The P-gp expressions in membrane protein in cortex and hippocampus were significantly increased in CHA and PVL +CHA rats, especially in PVL + CHA rats, while remarkably increased phosphorylated ERK1/2 was only found in PVL +CHA rats. Expressions of tight junction proteins claudin-5 and occluding in rat brain remained unchanged. In vitro data showed that NH4Cl increased reactive oxygen species, membrane expression and function of P-gp as well as phosphorylated ERK1/2 levels in HCMEC/D3. The NH4Cl-induced alterations were reversed by reactive oxygen species scavenger N-acetylcysteine and ERK1/2 inhibitor U0126. In conclusion, PVL+CHA increased function and membrane translocation of P-gp at rat BBB partly via ammonia. Reactive oxygen species/ERK1/2 pathway activation may be one of the reasons that ammonia upregulated P-gp expression and function at BBB.