Jia Weiyi, Liu Jiajia, Hu Rui, Hu Anling, Tang Weiwei, Li Lijuan, Li Jin
Key Laboratory of Infectious Disease and Biosafety, and Provincial Department of Education, Zunyi Medical University, Zunyi, China.
Research Center for Medicine and Biology, Zunyi Medical University, Zunyi, China.
Front Pharmacol. 2020 Apr 16;11:382. doi: 10.3389/fphar.2020.00382. eCollection 2020.
Oxidative stress induced by high ammonia, which leads to astrocyte edema, is the key to acute hepatic encephalopathy (AHE). Nuclear factor erythroid 2-related factor 2 (NRF2) has been implicated in oxidative stress, but the mechanism of NRF2 against ammonia-induced astrocytes edema has not been fully studied. We confirmed that the NRF2 pathway is related to brain edema caused by AHE and found that Xiaochaihutang (XCHT) could effectively activate the NRF2 pathway to treat AHE. The model of AHE was established with thioacetamide (TAA) in rats. Rat behaviors were observed, brain water content, blood ammonia levels, glutamine synthetase (GS), malondialdehyde (MDA), and total superoxide dismutase (T-SOD) were determined after XCHT treatment. Furthermore, the expression of NRF2 pathway proteins and mRNA, glial fibrillary acidic protein (GFAP) and aquaporins 4 (AQP4) were examined. In order to determine whether XCHT has a direct effect on cerebral edema caused by high ammonia, we examined the effect of XCHT compound serum on cortical astrocytes in the presence of ammonia, through microscopic observation and immunofluorescence (IF). Results showed that AHE induced by TAA changed the behavior of the rats, and increased brain water content, blood ammonia levels, GS and MDA content meanwhile decreasing T-SOD, but these symptoms were improved by treatment with XCHT. XCHT protected brain edema by activating the NRF2 pathway and increasing the expression of downstream proteins and genes. Astrocytes treated with 5 mM ammonia also showed an increase in the AQP4 protein expression but a decrease in XCHT compound serum and ammonia-induced cell edema groups. This study demonstrates that the NRF2 pathway is involved in the brain edema in AHE, and XCHT may represent a useful prescription for the treatment of AHE.
高氨诱导的氧化应激会导致星形胶质细胞水肿，是急性肝性脑病（AHE）的关键所在。核因子红细胞2相关因子2（NRF2）与氧化应激有关，但NRF2对抗氨诱导的星形胶质细胞水肿的机制尚未得到充分研究。我们证实NRF2通路与AHE引起的脑水肿有关，并发现小柴胡汤（XCHT）可有效激活NRF2通路来治疗AHE。用硫代乙酰胺（TAA）在大鼠中建立AHE模型。观察大鼠行为，在XCHT治疗后测定脑含水量、血氨水平、谷氨酰胺合成酶（GS）、丙二醛（MDA）和总超氧化物歧化酶（T-SOD）。此外，检测NRF2通路蛋白和mRNA、胶质纤维酸性蛋白（GFAP）和水通道蛋白4（AQP4）的表达。为了确定XCHT对高氨引起的脑水肿是否有直接作用，我们通过显微镜观察和免疫荧光（IF）检测了XCHT复方血清在有氨存在的情况下对皮质星形胶质细胞的影响。结果显示，TAA诱导的AHE改变了大鼠的行为，增加了脑含水量、血氨水平、GS和MDA含量，同时降低了T-SOD，但这些症状通过XCHT治疗得到改善。XCHT通过激活NRF2通路并增加下游蛋白和基因的表达来保护脑水肿。用5 mM氨处理的星形胶质细胞也显示AQP4蛋白表达增加，但在XCHT复方血清和氨诱导的细胞水肿组中减少。本研究表明NRF2通路参与AHE中的脑水肿，XCHT可能是治疗AHE的有效方剂。
