Department of Neurology, Wuxi People's Hospital of Nanjing Medical University, Wuxi, Jiangsu 214023, China.
Neurochem Int. 2011 Jun;58(7):812-9. doi: 10.1016/j.neuint.2011.03.007. Epub 2011 Mar 21.
As a physical barrier to regenerating axons, reactive astrogliosis is also a biochemical barrier which can secrete inhibitory molecules, including chondroitin sulfate proteoglycans (CSPGs) in the pathological mechanism of spinal cord injury (SCI). Thus, inhibition of astroglial proliferation and CSPG production might facilitate axonal regeneration after SCI. Recent studies have demonstrated that epidermal growth factor receptor (EGFR) activation triggers quiescent astrocytes into becoming reactive astrocytes and forming glial scar after CNS injury. In the present study, we investigated whether a specific EGFR inhibitor (AG1478) could attenuate the reactive astrogliosis and production of CSPGs, alleviate demyelination, and eventually enhance the functional recovery after SCI in rats. Our results showed that pEGFR immunoreactivity was up-regulated significantly post injury, mainly confined to astrocytes. Meanwhile, astrocytes near the injury site after SCI became activated obviously characterized by hypertrophic morphology and enhanced GFAP expression. However, administration of AG1478 remarkably reduced trauma induced-reactive astrogliosis and accumulation of CSPGs. Furthermore, the treatment with AG1478 also alleviated demyelination, increased expression of growth-associated proteins-43 (GAP-43) and improved hindlimb function after SCI. Therefore, the local blockade of EGFR in an injured area is beneficial to functional outcome by facilitating a more favorable environment for axonal regeneration in SCI rats.
作为轴突再生的物理障碍,反应性星形胶质细胞也是一种生化障碍,可分泌抑制性分子,包括在脊髓损伤 (SCI) 的病理机制中的软骨素硫酸盐蛋白聚糖 (CSPGs)。因此,抑制星形胶质细胞增殖和 CSPG 产生可能有助于 SCI 后轴突再生。最近的研究表明,表皮生长因子受体 (EGFR) 的激活会触发静息星形胶质细胞转变为反应性星形胶质细胞,并在中枢神经系统损伤后形成神经胶质瘢痕。在本研究中,我们研究了特定的 EGFR 抑制剂 (AG1478) 是否可以减轻反应性星形胶质细胞增生和 CSPGs 的产生,减轻脱髓鞘,并最终增强 SCI 后大鼠的功能恢复。我们的结果表明,pEGFR 免疫反应性在损伤后显著上调,主要局限于星形胶质细胞。同时,SCI 后损伤部位附近的星形胶质细胞明显被激活,表现为肥大的形态和增强的 GFAP 表达。然而,AG1478 的给药显著减少了创伤诱导的反应性星形胶质细胞增生和 CSPGs 的积累。此外,AG1478 的治疗还减轻了脱髓鞘,增加了生长相关蛋白-43 (GAP-43) 的表达,并改善了 SCI 后的后肢功能。因此,在损伤区域局部阻断 EGFR 有利于 SCI 大鼠的功能恢复,为轴突再生创造更有利的环境。