Radioprotective Effect of Melatonin on the Cervical Spinal Cord in Irradiated Rats

Objective: it has been suggested that the vascular endothelial growth factor (vegf) gene expression plays an important role in radiation-induced injury to the spinal cord. this study assesses the radioprotective effects of n-acetyl-5-methoxytryptamine (melatonin) through its modulation of vegf expression after localized irradiation of the cervical spinal cord.materials and methods: in this experimental study, we divided 192 male rats into four groups: 1. control (n=48); 2. rats that received an intraperitoneal (ip) injection of melatonin (n=48); 3. rats that received an ip injection of melatonin 30 minutes prior to cervical spinal cord gamma irradiation [dose: 22 gy; (n=48)]; and 4. rats that received an ip injection of vehicle prior to spinal cord irradiation (n=48). the changes in vegf expression were assessedusing real-time rt-pcrand enzyme-linked immunosorbent assays. samples forlightmicroscopywerestainedwithhematoxylinandeosin(h&e).thedifferencesamongthegroups were analyzed using the analysis of variance (anova)test followed by tukey’smultiple comparisons test.results: up-regulation of vegf expression was observed from 8 to 22 weeks after irradiation (p < 0.05). paralysis and other radiation-induced myelopathy manifestationsdeveloped within 22 weeks after irradiation. vegf expression in the melatoninpre-treatmentgroupsignificantlydown-regulatedinthe20th and 22 weeks after irradiationcompared to the radiation-only group.ndconclusion: the results support the hypothesis that modulation of vegf expression by melatonin administration may increase the survival rate of irradiated animals.