Department of Anatomy, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan.
J Pineal Res. 2014 Apr;56(3):322-32. doi: 10.1111/jpi.12125. Epub 2014 Mar 2.
Activation of proliferation of Schwann cells is crucial for axonal guidance and successful nerve regeneration following peripheral nerve injury (PNI). Considering melatonin plays an important role in proliferative regulation of central glial cells, the present study determined whether melatonin can effectively promote Schwann cell proliferation and improve nerve regeneration after PNI. The spontaneous immortalized rat Schwann cell line (RSC 96 cells) was first analyzed by quantitative polymerase chain reaction (QPCR) to detect the potential existence of melatonin receptors. The melatonin receptor-mediated signaling responsible for proliferation was examined by measuring the phosphorylation of extracellular signal-regulated kinases (ERK1/2) pathway. The in vivo model of PNI was performed by the end-to-side neurorrhaphy. The quantity of Schwann cells as well as the number of re-innervated motor end plates (MEP) on target muscles was examined to represent the functional recovery of injured nerves. QPCR results indicated that MT1 is the dominant receptor in Schwann cells. Immunoblotting and proliferation assay revealed an enhanced phosphorylation of ERK1/2 and increased number of RSC 96 cells following melatonin administration. Nonselective melatonin receptor antagonist (luzindole) treatment significantly suppressed all the above findings, suggesting that the proliferative effects of melatonin were mediated by a receptor-dependent pathway. In vivo results corresponded well with in vitro findings in which melatonin effectively increased the amount of proliferated Schwann cells and re-innervated MEP on target muscles following PNI. As melatonin successfully improves nerve regeneration by promoting Schwann cell proliferation, therapeutic use of melatonin may thus serve as a promising strategy to counteract the PNI-induced neuronal disability.
雪旺细胞的增殖激活对于周围神经损伤（PNI）后的轴突导向和成功神经再生至关重要。鉴于褪黑素在中枢神经胶质细胞的增殖调节中发挥重要作用，本研究旨在确定褪黑素是否能有效促进 PNI 后雪旺细胞增殖和改善神经再生。首先通过定量聚合酶链反应（QPCR）分析自发永生化大鼠雪旺细胞系（RSC 96 细胞），以检测褪黑素受体的潜在存在。通过测量细胞外信号调节激酶（ERK1/2）通路的磷酸化，检测褪黑素受体介导的增殖信号。通过端侧神经吻合术建立 PNI 的体内模型。通过检测靶肌肉上雪旺细胞的数量和再支配的运动终板（MEP）的数量来代表损伤神经的功能恢复。QPCR 结果表明 MT1 是雪旺细胞中的主要受体。免疫印迹和增殖试验表明，褪黑素给药后 ERK1/2 磷酸化增强，RSC 96 细胞数量增加。非选择性褪黑素受体拮抗剂（luzindole）处理显著抑制了上述所有发现，表明褪黑素的增殖作用是通过受体依赖性途径介导的。体内结果与体外结果一致，褪黑素有效增加了 PNI 后增殖的雪旺细胞数量和再支配的靶肌肉 MEP。由于褪黑素通过促进雪旺细胞增殖成功改善神经再生，因此褪黑素的治疗用途可能是对抗 PNI 引起的神经元功能障碍的一种有前途的策略。
