Moderate swimming exercise and caffeine supplementation reduce the levels of inflammatory cytokines without causing oxidative stress in tissues of middle-aged rats

The levels of circulatory inflammatory markers, including interleukin (IL) IL-1β, IL-6, tumor necrosis factor-α (TNF-α) and interferon (INF-γ), are known to increase associated to aging. Caffeine has been reported to produce many beneficial effects for health. Exercise is considered to be a safe medicine to attenuate inflammation and cellular senescence. The purpose of the present study was to investigate the effects of a moderate-intensity swimming exercise (3 % of body weight, 20 min per day, 4 weeks) and sub-chronic supplementation with caffeine (30 mg/kg, 4 weeks) on the serum cytokine levels in middle-aged (18 months) Wistar rats. The effects of swimming exercise and caffeine on oxidative stress in muscle and liver of middle-aged rats were also investigated. The two-way ANOVA of pro-inflammatory cytokine levels demonstrated a significant exercise x caffeine interaction for IL-1β (F _{(1, 16)} = 9.5772; p = 0.0069), IL-6 (F _{(1, 16)} = 8.0463; p = 0.0119) and INF-γ (F _{(1, 16)} = 15.078; p = 0.0013). The two-way ANOVA of TNF-α levels revealed a significant exercise × caffeine interaction (F _{(1, 16)} = 9.6881; p = 0.00670). Swimming exercise and caffeine supplementation increased the ratio of reduced glutathione/oxidized glutathione in the rat liver and gastrocnemius muscle. Hepatic and renal markers of damage were not modified. In conclusion, a moderate-intensity swimming exercise protocol and caffeine supplementation induced positive adaptations in modulating cytokine levels without causing oxidative stress in muscle and liver of middle-aged rats.