Effects of Melatonin on Neural Reconstruction and Motor Recovery through Regulation of Endoplasmic Reticulum Stress Response and Autophagy in Spinal Cord Injured Animal

Abstract

Autophagy and endoplasmic reticulum (ER) stress response are known to cause improved motor function and reduced damage of axons after spinal cord injury. This study aims to elucidate the effects of melatonin treatment on neural reconstruction and motor recovery through regulation of ER stress response and autophagy.
 Expression of neural and autophagic markers at mRNA level increased in injured experimental animals. And much higher increase of those markers was observed when treated with melatonin. Especially, at day 3, 28 after SCI, NG2 expression was increased at the injured site when treated with melatonin (p<.05). With melatonin treatment, LC3 expression was also increased at day 28 after surgery (p<.05). There was a tendency for spinal cord injured groups and melatonin‐treated groups to show increased ER stress response markers, when compared with the expression of non‐injured groups and non‐melatonin‐treated groups, respectively. Furthermore, more axonal sprouting and relatively intact morphology were observed in melatonin‐treated groups. Locomotor function was also improved when treated with melatonin.
 In conclusion, melatonin treatment promoted the neural reconstruction of both neuronal and glial cells. It also reduced autophagic cell death and, consequently brought improved locomotor function.Funding : 2012R1A1A2005089, 2013R1A2A2A01067169, KGM4611512, 2014R1A1A3051724