Pituitary adenylate cyclase-activating polypeptide plays an anti-inflammatory role in endotoxin-induced airway inflammation: In vivo study with gene-deleted mice

► In pituitary adenylate-cyclase polypeptide gene-deleted (PACAP−/−) mice, airway hyperreactivity is significantly higher 24 h after intranasal endotoxin administration and inflammatory histopathological changes are more severe both 6 h and 24 h later. ► Endotoxin-induced increase of myeloperoxidase (MPO) activity in the lung is almost double in PACAP−/− mice compared to the wild-types at 6 h. ► In contrast, there is no difference between the IL-1β concentrations of the lung of PACAP+/+ and PACAP−/− mice.