Minich Tobias, Riemer Jan, Schulz Jörg B, Wielinga Peter, Wijnholds Jan, Dringen Ralf
Institute for Biochemistry, University of Tuebingen, Germany.
J Neurochem. 2006 Apr;97(2):373-84. doi: 10.1111/j.1471-4159.2006.03737.x. Epub 2006 Mar 15.
Astrocytes play an important role in the glutathione (GSH) metabolism of the brain. To test for an involvement of multidrug resistance protein (Mrp) 1 and 5 in the release of GSH and glutathione disulfide (GSSG) from astrocytes, we used astrocyte cultures from wild-type, Mrp1-deficient [Mrp1(-/-)] and Mrp5-deficient [Mrp5(-/-)] mice. During incubation of wild-type or Mrp5(-/-) astrocytes, GSH accumulated in the medium at a rate of about 3 nmol/(h.mg), whereas the export of GSH from Mrp1(-/-) astrocytes was only one-third of that. In addition, Mrp1(-/-) astrocytes had a 50% higher specific GSH content than wild-type or Mrp5(-/-) cells. The presence of 50 microm of the Mrp inhibitor MK571 inhibited the rate of GSH release from wild-type and Mrp5(-/-) astrocytes by 60%, but stimulated at the low concentration of 1 microm GSH release by 40%. In contrast, both concentrations of MK571 did not affect GSH export from Mrp1(-/-) astrocytes. Moreover, in contrast to wild-type and Mrp5(-/-) cells, GSSG export during H(2)O(2) stress was not observed for Mrp1(-/-) astrocytes. These data demonstrate that in astrocytes Mrp1 mediates 60% of the GSH export, that Mrp1 is exclusively responsible for GSSG export and that Mrp5 does not contribute to these transport processes.
星形胶质细胞在大脑的谷胱甘肽（GSH）代谢中发挥着重要作用。为了检测多药耐药蛋白（Mrp）1和5是否参与星形胶质细胞释放GSH和谷胱甘肽二硫化物（GSSG），我们使用了来自野生型、Mrp1缺陷型[Mrp1(-/-)]和Mrp5缺陷型[Mrp5(-/-)]小鼠的星形胶质细胞培养物。在野生型或Mrp5(-/-)星形胶质细胞的孵育过程中，GSH以约3 nmol/(h·mg)的速率在培养基中积累，而Mrp1(-/-)星形胶质细胞的GSH输出量仅为其1/3。此外，Mrp1(-/-)星形胶质细胞的比GSH含量比野生型或Mrp5(-/-)细胞高50%。50 μmol的Mrp抑制剂MK571使野生型和Mrp5(-/-)星形胶质细胞的GSH释放速率降低60%，但在1 μmol的低浓度下却使GSH释放增加40%。相比之下，两种浓度的MK571均不影响Mrp1(-/-)星形胶质细胞的GSH输出。此外，与野生型和Mrp5(-/-)细胞不同，在H2O2应激期间未观察到Mrp1(-/-)星形胶质细胞有GSSG输出。这些数据表明，在星形胶质细胞中，Mrp1介导了60%的GSH输出，Mrp1是GSSG输出的唯一负责者，而Mrp5不参与这些转运过程。
