Pituitary Adenylate Cyclase-Activating Polypeptide Prevents Mortality Caused by Septic Peritonitis in Mice

The purpose of this study was to investigate whether pituitary adenylate cyclase-activating polypeptide (PACAP) prevents mortality due to sepsis in mice. Mice were given PACAP at designated time points before or after cecal ligation and puncture (CLP), and organ injury and mortality were investigated. Serum inflammatory and anti-inflammatory cytokine levels were assessed after CLP. Plasma corticosterone and adrenocorticotropic hormone levels were also measured. Isolated tissue macrophages (Mfs) were incubated with or without PACAP, and production of cytokines was measured. Activation of NF-κB was investigated in tissue Mfs isolated from CLP animal in the presence and absence PACAP in vitro. PACAP treatment significantly prevented acute lung injury and mortality after CLP. Plasma endotoxin levels and bacterial load were not different between PACAP-treated and nontreated groups. Increased serum TNF-α and HMGB1 levels in animals treated with vehicle were significantly blunted in PACAP-treated animals after CLP. Furthermore, serum IL-10 levels were significantly greater in the PACAP-treated group compared with the vehicle group. Production of HMGB1 and TNF-α by isolated hepatic Mfs was significantly inhibited in the presence of PACAP, whereas production of IL-10 by isolated hepatic Mfs and interstitial lung Mfs was significantly increased. Plasma corticosterone and adrenocorticotropic hormone levels were significantly greater in the animals treated with PACAP compared with vehicle after CLP. Activation of NF-κB was significantly inhibited by PACAP in the hepatic Mfs compared with other tissue Mfs. PACAP prevents mortality due to septic peritonitis by inhibiting inflammation via NF-κB activation and possible effects on the brain.