Melatonin modulates the expression of "vascular endothelial growth factor" gene in irradiated rat cervical spinal cord

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It is suggested that vascular endothelial growth factor (VEGF) gene expression has an important role in inducing radiation injury to the spinal cord. In this study, the radioprotective effect of melatonin on the VEGF expression was assessed after localized irradiation of cervical spinal cord. A number of rats were divided into four groups: 1. Control group; 2. Group that was given an intraperitonial injection of melatonin (100 mg/kg body weight); 3. Group of rats which got melatonin and cervical spinal cord irradiation with 22 Gy gamma irradiation 30 minutes later; and 4. Group that was given an intraperitonial injection of vehicle and radiation to the spinal cord. The changes in VEGF expression were assessed using realtime reverse transcription-polymerase chain reaction (RTPCR). Upregulation of VEGF expression was observed from 8 to 22 weeks after irradiation (P<0.05). Paralysis and other radiation myelopathy manifestations developed within 22 weeks after irradiation. VEGF gene expression in melatonin pretreatment group compared with radiation group was significantly down-regulated in the 20th and 22nd weeks after irradiation. The present researchers tried to outline the variations in the expresion profile of VEGF gene within the rats' cervical spinal cords in the periods of 4 hours to 22 weeks after 22 Gy single dose gamma irradiation. The results support the hypothesis that modulation of VEGF gene expression by melatonin administration may increase the survival rate of irradiated animals. © 2009 Springer-Verlag.