Rapid non-genomic effects of glucocorticoids on oxidative stress in a guinea pig model of asthma

Background and objective: Glucocorticoids (GC) may exert therapeutic effects in asthma by a rapid non‐genomic mechanism. The lungs of asthmatic patients are exposed to oxidative stress, which is believed to be critical in the pathogenesis of asthma. The aim of this study was to investigate whether GC exert a rapid non‐genomic effect on oxidative stress in asthmatic guinea pigs. Methods: The guinea pig asthma model was used to assess inhibitory effects of budesonide (BUD) on oxidative stress. BAL fluid (BALF), trolox equivalent antioxidant capacity and lung manganese superoxide dismutase (MnSOD) activity were measured by spectrophotometry. Superoxide anion production was measured by cytochrome c reduction assay. Results: Oxidative stress occurred within minutes following antigen challenge and BUD reduced the severity of oxidative stress in asthmatic guinea pigs within 15 min. BUD significantly decreased BALF trolox equivalent antioxidant capacity and lung MnSOD activity, as compared with those of vehicle‐treated asthmatic guinea pigs (P