Resistance exercise attenuates skeletal muscle oxidative stress, systemic pro-inflammatory state, and cachexia in Walker-256 tumor-bearing rats.

Abstract

The aim of this study was to investigate the effects of resistance exercise training (RET) on oxidative stress, systemic inflammatory markers and muscle wasting in Walker-256 tumor-bearing rats. Male (Wistar) rats were divided into 4 groups: sedentary controls (n=9); tumor-bearing (n=9); exercised (n=9); and tumor-bearing exercised (n=10). Exercised and tumor-bearing exercised rats were exposed to resistance exercise of climbing a ladder apparatus with weights tied to their tails during 6-wks. The physical activity of control and tumor-bearing rats was confined to the space of the cage. After this period, tumor-bearing and tumor-bearing exercised animals were inoculated subcutaneously with Walker-256 tumor cells (11.0x107 cells in 0.5 ml of PBS) while control and exercised rats were injected with vehicle. Following inoculation, rats maintained resistance exercise training (exercised and tumor-bearing exercised) or sedentary behavior (control and tumor-bearing) for 12 more days, after which they were euthanized. Results showed muscle wasting in T animals, with body weight loss, increased systemic leukocytes and inflammatory interleukins as well as muscular oxidative stress and reduced mTOR signaling. In contrast, RET in tumor-bearing exercised group was able to mitigate the reduced body weight and muscle wasting with the attenuation of muscle oxidative stress and systemic inflammatory markers. RET also prevented loss of muscle strength associated with tumor development. RET however, did not prevent the muscle proteolysis signaling via FBXO32 gene mRNA expression in tumor-bearing group. In conclusion, RET performed prior tumor implantation prevents cachexia development by attenuating tumor-induced systemic pro-inflammatory condition with muscle oxidative stress and muscle damage.