Protective effects of insulin-like growth factor-I on the decrease in myogenic differentiation by ionizing radiation

Purpose: The aim of the work is to evaluate the effects of insulin-like growth factor-1 (IGF-1) on the decrease in myotube formation induced by ionizing radiation. Materials and methods: We induced C2C12 cells to a myogenic linage following X-ray irradiation at 2 and 4Gy. Myogenic differentiation was estimated using immnocytochemical staining with anti-myosin antibody, and the anti-myosin antibody positive areas, the total number of nuclei, the number of nuclei included in multinucleated myotubes per field, and the myotube formation ratio were analyzed. Results: In the myogenic differentiation in the presence of IGF-1, the decrease in anti-myosin antibody positive areas, the nuclei included in myotubes, and the myotube formation ratio induced by X-ray irradiation at 2Gy was restored to control levels. Conclusions: The addition of IGF-1 protected against the decrease myotube formation induced by X-ray irradiation at 2Gy. Since X-ray irradiation at 2Gy is usually used for multi-fractionated irradiation in radiotherapy, our findings suggest that IGF-1 could be useful to protect against impairment of muscle repair induced by therapeutic dose radiation.