Lingor Paul, Tönges Lars, Pieper Nicole, Bermel Christina, Barski Elisabeth, Planchamp Veronique, Bähr Mathias
1Department of Neurology, Georg-August-University Göttingen, University Medicine, Waldweg 33, 37073 Göttingen, Germany.
Brain. 2008 Jan;131(Pt 1):250-63. doi: 10.1093/brain/awm284. Epub 2007 Dec 5.
Functional regeneration in the CNS is limited by lesion-induced neuronal apoptosis and an environment inhibiting axonal elongation. A principal, yet unresolved question is the interaction between these two major factors. We thus evaluated the role of pharmacological inhibition of rho kinase (ROCK), a key mediator of myelin-derived axonal growth inhibition and CNTF, a potent neurotrophic factor for retinal ganglion cells (RGC), in models of retinal ganglion cell apoptosis and neurite outgrowth/regeneration in vitro and in vivo. Here, we show for the first time that the ROCK inhibitor Y-27632 significantly enhanced survival of RGC in vitro and in vivo. In vitro, the co-application of CNTF and Y-27632 potentiated the effect of either substance alone. ROCK inhibition resulted in the activation of the intrinsic MAPK pathway, and the combination of CNTF and Y-27632 resulted in even more pronounced MAPK activation. While CNTF also induced STAT3 phosphorylation, the additional application of ROCK inhibitor surprisingly diminished the effects of CNTF on STAT3 phosphorylation. ROCK activity was also decreased in an additive manner by both substances. In vivo, both CNTF and Y-27632 enhanced regeneration of RGC into the non-permissive optic nerve crush model and additive effects were observed after combination treatment. Further evaluation using specific inhibitors delineate STAT3 as a negative regulator of neurite growth and positive regulator of cell survival, while MAPK and Akt support neurite growth. These results show that next to neurotrophic factors ROCK inhibition by Y-27632 potently supports survival of lesioned adult CNS neurons. Co-administration of CNTF and Y-27632 results in additive effects on neurite outgrowth and regeneration. The interaction of intracellular signalling pathways may, however, attenuate more pronounced synergy and has to be taken into account for future treatment strategies.
中枢神经系统（CNS）中的功能再生受到损伤诱导的神经元凋亡以及抑制轴突伸长的环境的限制。一个主要但尚未解决的问题是这两个主要因素之间的相互作用。因此，我们在体外和体内视网膜神经节细胞（RGC）凋亡以及神经突生长/再生模型中，评估了对Rho激酶（ROCK，髓磷脂源性轴突生长抑制的关键介质）进行药理学抑制以及睫状神经营养因子（CNTF，一种对视网膜神经节细胞有强大营养作用的因子）的作用。在此，我们首次表明ROCK抑制剂Y-27632在体外和体内均能显著提高视网膜神经节细胞的存活率。在体外，联合应用CNTF和Y-27632可增强单独使用任何一种物质的效果。抑制ROCK导致内在丝裂原活化蛋白激酶（MAPK）途径的激活，而CNTF与Y-27632的联合使用导致更明显的MAPK激活。虽然CNTF也诱导信号转导子和转录激活子3（STAT3）磷酸化，但额外应用ROCK抑制剂出人意料地减弱了CNTF对STAT3磷酸化的作用。两种物质还以相加的方式降低了ROCK活性。在体内，CNTF和Y-27632均增强了视网膜神经节细胞在非允许性视神经挤压模型中的再生，联合治疗后观察到相加效应。使用特异性抑制剂的进一步评估表明，STAT3是神经突生长的负调节因子和细胞存活的正调节因子，而MAPK和蛋白激酶B（Akt）支持神经突生长。这些结果表明，除了神经营养因子外，Y-27632抑制ROCK能有效地支持受损成年中枢神经系统神经元的存活。联合使用CNTF和Y-27632对神经突生长和再生产生相加效应。然而，细胞内信号通路的相互作用可能会减弱更明显的协同作用，在未来的治疗策略中必须加以考虑。
