BACKGROUNDBronchial asthma (BA) and chronic obstructive pulmonary disease (COPD) are both inflammatory airway diseases with different characteristics. However, there are many patients who suffer from both BA and COPD. This study was to evaluate changes of inflammatory airway features and hypothalamic-pituitary-adrenal (HPA) axis function in asthmatic rats combined with COPD.

METHODSBrown Norway (BN) rats were used to model the inflammatory airway diseases of BA, COPD and COPD + BA. These three models were compared and evaluated with respect to clinical symptoms, pulmonary histopathology, airway hyperresponsiveness (AHR), inflammatory cytokines and HPA axis function.

RESULTSThe inflammatory airway features and HPA axis function in rats in the COPD + BA model group were greatly influenced. Rats in this model group showed features of the inflammatory diseases BA and COPD. The expression of inflammatory cytokines in this model group might be up or downregulated when both disease processes are present. The levels of corticotrophin releasing hormone mRNA and corticosterone in this model group were both significantly decreased than those in the control group (P < 0.05).

CONCLUSIONSBN rat can be used as an animal model of COPD + BA. By evaluating this animal model we found that the features of inflammation in rats in this model group seem to be exaggerated. The HPA axis functions in rats in this model group have been disturbed or impaired, which is prominent at the hypothalamic level.