Mitochondria‐Targeted Catalase Does Not Enhance Myogenesis following Cardiotoxin Muscle Injury and Radiation Exposure

Abstract

Radiation inhibits myogenesis following muscle damage from cardiotoxin (CTX) injection. Cellular oxidative stress may contribute to this inhibition. The objective of the current study was to investigate the effects of human mitochondrial‐targeted catalase (MCAT) following muscle damage induced by cardiotoxin with and without exposure to radiation. Adult male mice (C57BL/J6) were assigned to one of eight groups: CTX wild‐type or CTX+MCAT; irradiation (IRR) or no IRR; and 4 or 14 days. Following CTX injection into the tibialis anterior (TA), mice assigned to the irradiation groups were exposed to a dose of 7 Gy of gamma irradiation. The TA muscles of both legs were harvested and stained by hematoxylin and eosin for histological analysis. Cross sectional area (CSA) of regenerating fibers (centralized nuclei) was analyzed. No significant differences in CSA were found between wild‐type and MCAT mice at days 4 or 14. Irradiation resulted in significant damage at day 4 in both wild‐type and MCAT mice with no centralized nuclei discernable. Irradiation caused a significant blunting of regeneration at day 14 compared to the non‐irradiated groups (p < 0.001) with no significant difference between CTX+IRR and CTX+MCAT+IRR. These results indicate that a single dose of clinically relevant radiation resulted in the inhibition of myogenesis 14 days following CTX injection that was not affected by catalase targeted to the mitochondria.