Effect of 8% Caloric Restriction and Lifelong Wheel Running Exercise on Oxidative Stress, MnSOD, and Cu-ZnSOD in the Fischer-344 Rat Plantaris

Abstract

Aging is characterized by a reduction in skeletal muscle is a reduction of muscle mass or sarcopenia, caused by reductions in fiber number and cross-sectional area. Increased oxidative stress and impaired stress-response may contribute to sarcopenia with aging and muscle wasting pathologies (e.g., COPD, cancer, AIDS, heart failure). Recently, we found that lifelong wheel running exercise combined with mild (8%) caloric restriction (8%CR) protects against age-induced muscle fiber atrophy and increased connective tissue in the rat plantaris. However the effect of lifelong wheel running and 8%CR on stress and redox-protective proteins such as antioxidant enzymes (MnSOD, Cu-ZnSOD) and heat shock proteins (HSPs) are unknown. PURPOSE: To determine if 8%CR and lifelong wheel running exercise alters MnSOD, Cu-ZnSOD, and HSPs in the plantaris of aging Fischer-344 rats. METHODS: Male Fischer-344 rats were divided into 4 groups at 11 weeks of age: ad libitum feeding until 6 mo. old (6AL, n=12); fed ad libitum until 24 mo. old (24AL, n=11); 8% CR to 24 mo of age (24CR, n=12); wheel running to 24 mo. + 8%CR (24ExCR, n=12). Protein expression of MnSOD, Cu-ZnSOD, HSP25, phosphorylated HSP25 (p-HSP25), HSP70, and HSP90 were determined using Western immunoblot analysis. RESULTS: MnSOD was not altered by age, 8%CR or exercise. Cu-ZnSOD protein expression was modestly higher in OAL (16%) and OEXCR (16%) than YAL. HSP25 (−46%) and p-HSP25 (−25%) levels were significantly decreased in OAL rats compared to YAL. However, HSP25 and p-HSP25 8%CR were significantly elevated in OCR (123%, 38%) and OExCR (50%, 108%) compared with OAL. No significant age, 8%CR, or exercise effects were found HSP70 and HSP90. CONCLUSIONS: Our findings suggest that HSP25 and p-HSP25 are potential regulatory mechanisms by which mild caloric restriction and lifelong exercise attenuate age-induced sarcopenia and remodeling in the plantaris of Fischer-344 rats.