What is the central question of this study? This study investigated the role of the endogenous anti-inflammatory
cytokine interleukin-10 in intense acute swimming-induced muscle
mechanical hyperalgesia in mice. What is the main finding and its importance? Endogenous
interleukin-10 has a key role in limiting exercise-induced
muscle pain in a model presenting similarities to delayed-onset
muscle soreness in mice.
Interleukin-10 reduced
muscle pain by diminishing leucocyte recruitment, hyperalgesic
cytokine production, oxidative stress and myocyte damage.
Interleukin-10 (IL-10) is an antihyperalgesic
cytokine. In this study, IL-10-deficient (IL-10(-/-) ) mice were used to investigate the role of endogenous
IL-10 in intense acute swimming-induced muscle
mechanical hyperalgesia, which presents similarities with delayed-onset
muscle soreness. An intense acute swimming session of 1 or 2 h induced significant muscle
mechanical hyperalgesia in a time-dependent manner in wild-type mice compared with the
sham group 24 h after the session, which was further increased in IL-10(-/-) mice (P ˂ 0.05). Intraperitoneal treatment of wild-type mice with
IL-10 (1-10 ng) reduced muscle
mechanical hyperalgesia in a dose-dependent manner and reversed the enhanced muscle
hyperalgesia in IL-10(-/-) mice (P ˂ 0.05). The 2 h swimming session induced increases in tumour
necrosis factor-α, interleukin-1β and
IL-10 production in the soleus muscle. However, tumour
necrosis factor-α and interleukin-1β production in the soleus muscle were even higher in IL-10(-/-) mice between 2 and 6 h after the stimulus (P ˂ 0.05). There was no statistical difference in the levels of the antihyperalgesic
cytokines interleukin-4,
interleukin-5,
interleukin-13 and
transforming growth factor-β between wild-type and IL-10(-/-) mice (P ˃ 0.05).
Interleukin-10 deficiency also resulted in increased
myeloperoxidase activity, greater depletion of
reduced glutathione levels, increased
superoxide anion production and the maintenance of high plasma concentrations of
creatine kinase (until 24 h after the swimming session) in soleus muscle (P ˂ 0.05). These results demonstrate that endogenous
IL-10 controls intense acute swimming-induced muscle
mechanical hyperalgesia by limiting oxidative stress and
cytokine production.