Knockouts of Se-glutathione peroxidase-1 and Cu,Zn superoxide dismutase exert different impacts on femoral mechanical performance of growing mice

The objective of this study was to determine the impact of knockout of Cu,Zn-superoxide dismutase (SOD1) and Se-glutathione peroxidase-1 (GPX1) on murine bone biomechanical properties. Femora samples were collected from wild-type (WT), SOD1-knockout SOD1(-/-)] and GPX1-knockout GPX1(-/-)] female mice (9-wk old, n = 7-8 per genotype) to assay for bone enzyme activities and mechanical properties in three point bending. Prior to testing, all mice were fed a torula yeast diet supplemented with 0.4 mg Se/kg as sodium selenite. Compared with the WT mice, SOD1(-/-) mice displayed a series of reductions (p < 0.05): 24% in body mass, 8% in femoral length, 43% in femoral structural strength, and 32% in bending stiffness. When differences in body size were accounted for, femoral failure moment in SOD1(-/-) mice remained lower (p < 0.05) than that of WT. Femoral tartrate resistant acid phosphatase activity in SOD1(-/-) was 47% greater (p < 0.05) than the WT. In contrast, GPX1(-/-) mice showed no significant differences in femoral mechanical properties from those of WT mice. In conclusion, knockout of SOD1 exerted a greater impact on femoral mechanical characteristics than that of GPX1 in growing mice.