The superoxide anion donor, potassium superoxide, induces pain and inflammation in mice through production of reactive oxygen species and cyclooxygenase-2

It is currently accepted that superoxide anion (O2•−) is an important mediator in pain and inflammation. The role of superoxide anion in pain and inflammation has been mainly determined indirectly by modulating its production and inactivation. Direct evidence using potassium superoxide (KO2), a superoxide anion donor, demonstrated that it induced thermal hyperalgesia, as assessed by the Hargreaves method. However, it remains to be determined whether KO2 is capable of inducing other inflammatory and nociceptive responses attributed to superoxide anion. Therefore, in the present study, we investigated the nociceptive and inflammatory effects of KO2. The KO2-induced inflammatory responses evaluated in mice were: mechanical hyperalgesia (electronic version of von Frey filaments), thermal hyperalgesia (hot plate), edema (caliper rule), myeloperoxidase activity (colorimetric assay), overt pain-like behaviors (flinches, time spent licking and writhing score), leukocyte recruitment, oxidative stress, and cyclooxygenase-2 mRNA expression (quantitative PCR). Administration of KO2 induced mechanical hyperalgesia, thermal hyperalgesia, paw edema, leukocyte recruitment, the writhing response, paw flinching, and paw licking in a dose-dependent manner. KO2 also induced time-dependent cyclooxygenase-2 mRNA expression in the paw skin. The nociceptive, inflammatory, and oxidative stress components of KO2-induced responses were responsive to morphine (analgesic opioid), quercetin (antioxidant flavonoid), and/or celecoxib (anti-inflammatory cyclooxygenase-2 inhibitor) treatment. In conclusion, the well-established superoxide anion donor KO2 is a valuable tool for studying the mechanisms and pharmacological susceptibilities of superoxide anion-triggered nociceptive and inflammatory responses ranging from mechanical and thermal hyperalgesia to overt pain-like behaviors, edema, and leukocyte recruitment.

Atividade da NADPH oxidase em granulócitos e células mononucleares de adolescentes e crianças asmáticos segundo a gravidade da doença / NADPH oxidase activity of granulocytes and mononuclear cells of asthmatic children according to the disease severity

Objetivo: Investigar a liberaçäo espontânea e estimulada (com forbol miristato acetato - PMA) de superóxido por granulócitos e células mononucleares de adolescentes e crianças asmáticos classificadas segundo os critérios do relatório Iniciativa Global para Asma (GINA) de 1997. Métodos: Selecionamos 30 pacientes de seis a quinze anos, e os classificamos como tendo asma intermitente leve (AIL, n=9), persistente leve (APL,n=8), persistente moderada (APM,n=7) e persistente grave (APG, n=6). Os granulócitos e células mononucleares foram fracionados a partir de amostras do sangue periféricos por gradiente de densidade descontínuo. A cinética de liberaçäo de superóxido (0,5,15,25, 45, e 60 minutos) foi avaliada segundo a reduçäo do citocromo c, especificamente inibida pela superóxido dismutase. Os resultados foram comparados com os de 18 adultos sadios por análise de variância. Resultados: A liberaçäo espontânea de superóxido pelos granulócitos foi significamente maior, aos 25 minutos, nos grupos APL, APM e APG comparado aos grupos de indivíduos sadios e AIL (p<0,05), aos 45 minutos nos grupos APL e APM e aos 60 minutos nos grupos APG. A liberaçäo de superóxido pelos granulócitos estimulados com PMA, foi significamente maior nos grupos APM e APG que nos indivíduos sadios, em todos os tempos. Näo houve diferença significativa na liberaçäo de superóxido por células mononucleares, estimuladas ou näo com PMA, entre os diversos grupos de asmáticos e indivíduos sadios