Muscle Fiber Cross-sectional Area Is Unaffected 14 Days Following A Clinical Dose Of Radiation

Abstract

Skeletal muscle regeneration has previously been shown to be blunted following a dose of 7 Gy gamma irradiation with cardiotoxin injury. It has yet to be established if the same dose of radiation effects non-injured skeletal muscle. PURPOSE: The objective of the current study was to investigate the effects of a 7 Gy dose of irradiation on the cross-sectional area (CSA) of the tibialis anterior (TA). METHODS: Adult male mice (C57BL/J6) were assigned to one of 6 groups: 1) 4 day control, 2) 4 day irradiated (IRR), 3) 7 day control, 4) 7 day IRR, 5) 14 day control, 6) 14 day IRR. Each mouse was injected with saline before irradiation as part of a larger study. Following injection, mice in the irradiation groups were exposed to a dose of 7 Gy of gamma irradiation which is considered to be a clinically relevant dose. Following each time period the TA was removed and prepared for histological analysis by hematoxylin and eosin staining. Approximately 100 fibers of each muscle sample were analyzed with ImageJ software to estimate average fiber CSA. Data were analyzed by one-way ANOVA in GraphPad Prism. RESULTS: No differences were found between control and IRR mean fiber size at any of the time periods. CONCLUSIONS: These results indicate that a dose of 7 Gy of gamma irradiation may blunt myogenesis following cardiotoxin injury but does not alter fiber CSA up to 14 days following exposure.