A role for hydrogen peroxide in inflammatory hyperalgesia of the mouse hindpaw

Abstract

Reactive oxygen species, including hydrogen peroxide (H₂O₂), are released from activated leucocytes and resident cells in the joint during inflammation. We hypothesize that H₂O₂ is an important mediator of inflammatory pain and, thus, the aim of our experiments was to investigate the effect of H₂O₂ on inflammation of the mouse hindpaw. We performed behavioural studies in CD1 mice to determine the effect of H₂O₂ on both thermal and mechanical hyperalgesia and oedema formation 20 minutes after intraplantar injection into the mouse hindpaw. The Hargreaves technique was used to test thermal hyperalgesia and a dynamic plantar aesthesiometer was used for mechanical hyperalgesia studies. Oedema was determined by measuring paw mass. Our experiments showed intraplantar injection of H₂O₂ (2200–8800 nmoles) causes significant thermal and mechanical hyperalgesia of the mouse hindpaw. H₂O₂ also causes significant oedema formation. Thus, we propose that H₂O₂ is a potential target for the treatment of inflammatory pain.