Down-Regulation of Hypoxia-Inducible Factor-1α by Hyperbaric Oxygen Attenuates the Severity of Acute Pancreatitis in Rats

Objectives: This study investigated the role of hypoxia-inducible factor 1 alpha (HIF-1 alpha) in acute pancreatitis (AP) and whether HIF-1 alpha is involved in the therapeutic effects of hyperbaric oxygen (HBO) on AP. Methods: Thirty Wistar rats with taurocholate-induced AP were randomly assigned to 3 groups (each group had 10 rats) receiving oxygen, HBO, or no therapeutic treatment 4 hours after induction. Ten healthy sham-operated rats also served as controls. The arterial oxygen saturation, PaO2, pH, lactate dehydrogenase in the arterial sera, and amylase and tumor necrosis factor alpha in the venous sera were measured 6 hours after induction. Pancreatic tissues were subjected to histopathologic analysis, immunohistochemical and Western-blotted analyses of HIF-1 alpha and vascular endothelial growth factor, and measuring of myeloperoxidase activity. Results: The HBO therapy attenuated the severity of acute pancreatitis; reduced histopathologic scores, dry weight-wet weight ratio of pancreatic tissues, and levels of amylase and lactate dehydrogenase; and elevated blood arterial oxygen saturation, PaO2, and pH values. The HBO therapy inhibited AP-induced up-regulation of HIF-1 alpha and its downstream effector vascular endothelial growth factor and the production of tumor necrosis factor alpha and myeloperoxidase activity. Conclusions: Hypoxia-inducible factor 1 alpha plays a key role in the pathogenesis of AP, and the ability to down-regulate the expression of HIF-1 alpha may partially explain the therapeutic effect of HBO on AP.