Department of Anatomy, Faculty of Medicine, Kuwait University, Kuwait.
Neurochem Int. 2013 Feb;62(3):221-31. doi: 10.1016/j.neuint.2012.12.018. Epub 2013 Jan 8.
Recently, we have shown that green tea (GT) consumption improves both reflexes and sensation in unilateral chronic constriction injury to the sciatic nerve. Considering the substantial neuroprotective properties of GT polyphenols, we sought to investigate whether (-)-epigallocatechin-3-gallate (EGCG) could protect the sciatic nerve and improve functional impairments induced by a crushing injury. We also examined whether neuronal cell apoptosis induced by the crushing injury is affected by EGCG treatment. Histological examination of sciatic nerves from EGCG-treated (50mg/kg; i.p.) showed that axonotmized rats had a remarkable axonal and myelin regeneration with significant decrease in the number of myelinated axonal fibers compared to vehicle-treated crush group. Similarly, ultrastructural evaluation of EGCG-treated nerves displayed normal unmyelinated and myelinated axons with regular myelin sheath thickness and normalized appearance of Schmidt-Lantermann clefts. Extracellular matrix displayed normal collagen fibers appearance with distinctively organized distribution similar to sham animals. Analysis of foot position and extensor postural thrust test showed a progressive and faster recovery in the EGCG-treated group compared to vehicle-treated animals. EGCG-treated rats showed significant increase in paw withdrawal thresholds to mechanical stimulation compared to vehicle-treated crush group. EGCG treatment also restored the mRNA expression of Bax, Bcl-2 and survivin but not that of p53 to sham levels on days 3 and 7 post-injury. Our results demonstrate that EGCG treatment enhanced functional recovery, advanced morphological nerve rescue and accelerated nerve regeneration following crush injury partly due to the down regulation of apoptosis related genes.
最近，我们已经表明，饮用绿茶（GT）可以改善单侧坐骨神经慢性缩窄性损伤的反射和感觉。考虑到 GT 多酚具有很强的神经保护特性，我们试图研究 (-)-表没食子儿茶素-3-没食子酸酯（EGCG）是否可以保护坐骨神经并改善挤压伤引起的功能障碍。我们还检查了挤压伤诱导的神经元细胞凋亡是否受 EGCG 处理的影响。用 EGCG 处理（50mg/kg；腹腔注射）的坐骨神经的组织学检查表明，轴突断裂大鼠的轴突和髓鞘再生明显，与对照组相比，有髓轴突纤维数量明显减少。同样，用 EGCG 处理的神经的超微结构评估显示正常的无髓和有髓轴突，有正常厚度的髓鞘和正常的施密特-兰登曼裂。细胞外基质显示正常胶原纤维外观，具有明显组织分布，类似于假手术动物。足部位置和伸肌姿势推力测试的分析表明，与对照组相比，EGCG 处理组的恢复速度更快。与对照组相比，EGCG 处理组的大鼠对机械刺激的足部撤回阈值明显增加。EGCG 处理还恢复了 Bax、Bcl-2 和 survivin 的 mRNA 表达，但在损伤后第 3 天和第 7 天，p53 的表达并未恢复到假手术水平。我们的研究结果表明，EGCG 治疗可增强挤压伤后的功能恢复、促进形态学神经挽救和加速神经再生，部分原因是下调了与凋亡相关的基因。
