Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska 68198, USA.
J Neurosci. 2011 Jan 12;31(2):414-25. doi: 10.1523/JNEUROSCI.5247-10.2011.
Inflammation attenuates gap junction (GJ) communication in cultured astrocytes. Here we used a well-characterized model of experimental brain abscess as a tool to query effects of the CNS inflammatory milieu on astrocyte GJ communication and electrophysiological properties. Whole-cell patch-clamp recordings were performed on green fluorescent protein (GFP)-positive astrocytes in acute brain slices from glial fibrillary acidic protein-GFP mice at 3 or 7 d after Staphylococcus aureus infection in the striatum. Astrocyte GJ communication was significantly attenuated in regions immediately surrounding the abscess margins and progressively increased to levels typical of uninfected brain with increasing distance from the abscess proper. Conversely, astrocytes bordering the abscess demonstrated hemichannel activity as evident by enhanced ethidium bromide (EtBr) uptake that could be blocked by several pharmacological inhibitors, including the connexin 43 (Cx43) mimetic peptide Gap26, carbenoxolone, the pannexin1 (Panx1) mimetic peptide (10)Panx1, and probenecid. However, hemichannel opening was transient with astrocytic EtBr uptake observed near the abscess at day 3 but not day 7 after infection. The region-dependent pattern of hemichannel activity at day 3 directly correlated with increases in Cx43, Cx30, Panx1, and glutamate transporter expression (glial L-glutamate transporter and L-glutamate/L-aspartate transporter) along the abscess margins. Changes in astrocyte resting membrane potential and input conductance correlated with the observed changes in GJ communication and hemichannel activity. Collectively, these findings indicate that astrocyte coupling and electrical properties are most dramatically affected near the primary inflammatory site and reveal an opposing relationship between the open states of GJ channels versus hemichannels during acute infection. This relationship may extend to other CNS diseases typified with an inflammatory component.
炎症可减弱培养的星形胶质细胞中的缝隙连接 (GJ) 通讯。在这里，我们使用一种经过充分表征的实验性脑脓肿模型作为工具，来探究中枢神经系统炎症环境对星形胶质细胞 GJ 通讯和电生理特性的影响。在星形胶质细胞绿色荧光蛋白 (GFP) 阳性的急性脑片中，在金黄色葡萄球菌感染纹状体 3 或 7 天后，对全细胞膜片钳记录进行了操作。在脓肿边缘附近的区域，星形胶质细胞的 GJ 通讯明显减弱，随着与脓肿本身的距离增加，逐渐增加至未感染大脑的典型水平。相反，与脓肿相邻的星形胶质细胞表现出半通道活性，如溴化乙锭 (EtBr) 摄取增强，这可被几种药理学抑制剂阻断，包括连接蛋白 43 (Cx43) 模拟肽 Gap26、carbenoxolone、pannexin1 (Panx1) 模拟肽 (10)Panx1 和丙磺舒。然而，半通道的开放是短暂的，在感染后第 3 天，在脓肿附近观察到星形胶质细胞 EtBr 摄取，但在第 7 天没有观察到。第 3 天半通道活性的区域依赖性模式与 Cx43、Cx30、Panx1 和谷氨酸转运体表达（胶质 L-谷氨酸转运体和 L-谷氨酸/L-天冬氨酸转运体）沿脓肿边缘的增加直接相关。星形胶质细胞静息膜电位和输入电导的变化与观察到的 GJ 通讯和半通道活性变化相关。总的来说，这些发现表明，星形胶质细胞偶联和电特性在原发性炎症部位附近受到的影响最大，并揭示了在急性感染期间 GJ 通道与半通道开放状态之间的相反关系。这种关系可能扩展到其他以炎症成分为特征的中枢神经系统疾病。
