Repair and Regeneration of Low Dose Ionizing Radiation to Injured Muscles using Barium Chloride in a Rat Model

The biological consequences of low dose ionizing radiation (LDIR) are strongly debated. While most studies confirm its detrimental effects, several studies suggest beneficial (hormetic) effects of LDIR as an anti-inflammatory agent on musculoskeletal injuries. The present study aimed to investigate the bio-stimulatory effects of LDIR (direct and indirect) in healing the musculoskeletal injuries induced by barium chloride (BaCl2). Thirty adult male Albino rats were used in this study and were divided into five groups as follows: control, BaCl2, g-rays (direct), g-rays (indirect), BaCl2 and g (direct), and BaCl2 and g (indirect) group. Muscle injury was induced using 50 ml of 1.2 % BaCl2. A single partial body dose of 0.5 Gy gamma rays was performed using Cesium-137 source on the right femur. Quantative real-time PCR was used to assess the role of the selected genes [Myogenin (MyoG), myogenic regulatory factors (Myf5), mitochondrial transcription factor A (Tfam), and nuclear respiratory factor (Nrf1)]. Biochemical and histological examination were also performed. As compared with the BaCl2 group the results demonstrated that the direct and remote (left femur) g-irradiation after BaCl2 injection caused a significant decrease in creatinine, urea, aspartate aminotransferase, alanine aminotransferase, creatine kinase, malondialdehyde levels together with a downregulation in the expression level of Myf5 m RNA. There was a significant elevation in reduced glutathione and catalase activities and a significant upregulation in the expression of MyoG m RNA and Tfam mRNA. The remote effect of g-irradiation after BaCl2 injection induced a significant decrease in lactate dehydrogenase activity and nitric oxide levels as well as a significant downregulation in the expression level of Nrf1m-RNA. Histological changes observed in regenerative muscle fibres included a prominent central ovoid nucleus, mild inflammation, and minimal infiltration of red blood cells, which were consistent with gene expression findings. In conclusion, the low dose of g-rays (0.5 Gy) promotes the regeneration of injured myofibers, and positively contributes to the treatment of muscular injury. It stimulated the expression of genes associated with muscle regeneration and differentiation, as well as genes that govern mitochondrial biogenesis. It reduced oxidative stress markers, enhanced the activities of antioxidant enzymes, and Q6 consequently improved and expedited muscle repair capacity