Reinehr Roland, Görg Boris, Becker Stephan, Qvartskhava Natalia, Bidmon Hans J, Selbach Oliver, Haas Helmut L, Schliess Freimut, Häussinger Dieter
Clinic for Gastroenterology, Hepatology and Infectiology, Heinrich Heine University, Moorenstrasse 5, D-40225 Düsseldorf, Germany.
Glia. 2007 May;55(7):758-71. doi: 10.1002/glia.20504.
The role of NADPH oxidase (NOX) and the regulatory subunit p47(phox) for hypoosmotic ROS generation was studied in cultured rat astrocytes and brain slices of wilde type and p47(phox) knock-out mice. Cultured rat astrocytes express mRNAs encoding for the regulatory subunit p47(phox), NOX1, 2, and 4, and the dual oxidases (DUOX)1 and 2, but not NOX3. Hypoosmotic (205 mosmol/L) swelling of cultured astrocytes induced a rapid generation of ROS that was accompanied by serine phosphorylation of p47(phox) and prevented by the NADPH oxidase inhibitor apocynin. Apocynin also impaired the hypoosmotic tyrosine phosphorylation of Src. Both, hypoosmotic ROS generation and p47(phox) serine phosphorylation were sensitive to the acidic sphingomyelinase inhibitors AY9944 and desipramine, the protein kinase C (PKC)zeta-inhibitory pseudosubstrate peptide, the NMDA receptor antagonist MK-801 and the intracellular Ca(2+) chelator BAPTA-AM. Also hypoosmotic exposure of wilde type mouse cortical brain slices increased ROS generation, which was allocated in part to the astrocytes and which was absent in presence of apocynin and in cortical brain slices from p47(phox) knock-out mice. Also ammonia induced a rapid ROS production in cultured astrocytes and brain slices, which was sensitive to apocynin. The data suggest that astrocyte swelling triggers a p47(phox)-dependent NADPH oxidase-catalyzed ROS production. The findings further support a close interrelation between osmotic and oxidative stress in astrocytes, which may be relevant to different brain pathologies including hepatic encephalopathy.
在野生型和p47（phox）基因敲除小鼠的培养大鼠星形胶质细胞和脑片中，研究了NADPH氧化酶（NOX）和调节亚基p47（phox）在低渗性活性氧生成中的作用。培养的大鼠星形胶质细胞表达编码调节亚基p47（phox）、NOX1、2和4以及双氧化酶（DUOX）1和2的mRNA，但不表达NOX3。培养的星形胶质细胞低渗（205 mosmol/L）肿胀诱导活性氧快速生成，同时伴有p47（phox）的丝氨酸磷酸化，且被NADPH氧化酶抑制剂夹竹桃麻素所抑制。夹竹桃麻素也损害了Src的低渗性酪氨酸磷酸化。低渗性活性氧生成和p47（phox）丝氨酸磷酸化均对酸性鞘磷脂酶抑制剂AY9944和地昔帕明、蛋白激酶C（PKC）ζ抑制性假底物肽、NMDA受体拮抗剂MK-801以及细胞内Ca（2+）螯合剂BAPTA-AM敏感。野生型小鼠皮质脑片的低渗暴露也增加了活性氧生成，部分活性氧生成归因于星形胶质细胞，在夹竹桃麻素存在时以及p47（phox）基因敲除小鼠的皮质脑片中则不存在这种情况。氨也诱导培养的星形胶质细胞和脑片中快速产生活性氧，且对夹竹桃麻素敏感。数据表明星形胶质细胞肿胀触发了p47（phox）依赖的NADPH氧化酶催化的活性氧生成。这些发现进一步支持了星形胶质细胞中渗透应激和氧化应激之间的密切相互关系，这可能与包括肝性脑病在内的不同脑部疾病有关。
