Modulation of Endogenous Nitric Oxide Synthase in Experimental Acute Pancreatitis: Role of Anti-ICAM-1 and Oxygen Free Radical Scavengers

Abstract

ObjectiveTo evaluate, in an experimental model of acute pancreatitis, the impact of nitric oxide on the disease process and the interaction between nitric oxide and oxygen free radicals. Summary Background DataNitric oxide and oxygen free radicals are involved in the pathophysiology of acute pancreatitis. It is well established that oxygen free radicals play an important role in the development of pancreatic cell damage and remote organ failure, but the impact of nitric oxide on the disease process and the interactions between the two radical species remain controversial. MethodsNecrotizing pancreatitis (NP) was induced in Wistar rats by intraductal sodium taurocholate infusion after pretreatment with isotonic saline (NP-S), superoxide dismutase/catalase (NP-SOD/CAT), or an anti-ICAM-1 antibody (aICAM-1). Sham-operated rats received isotonic saline (SHX). After an observation period of 5 minutes and 24 hours, the pancreas was removed for microscopy, glutathione, and myeloperoxidase (MPO) analysis. The inducible NO synthase (NOS-2) was detected by Western blotting or RT-PCR. Serum was analyzed for nitrite/nitrate (NO 2 -/NO 3-) and S-nitrosothioles (RSNO), while plasma was used to assay for trypsinogen activation peptides (TAP). ResultsNP-S animals showed a significant decrease in GSH levels after NP-induction as compared with animals under therapy. Increased MPO levels in the NP-S group were significantly reduced by aICAM-1 while SOD/CAT injection showed no changes. Serum NO-derivatives peaked at 12 hours while TAP levels had a maximum at 6 hours after NP induction, and were lower after aICAM-1 application SOD/CAT treatment increased both parameters. Extended acinar cell damage and inflammatory infiltrate developed in NP-S animals and was significantly improved by SOD/CAT and aICAM-1 treatment. RT-PCR and Western-blot analysis revealed NOS-2 expression in the NP-S group, which was reduced by radical scavengers and aICAM-1.

Free radicals and the pancreatic acinar cells: role in physiology and pathology

“…Oxidative stress was documented in pancreatic tissue by detecting generation of ROS with chemiluminescence (Gough et al 1990) or fluorescence (Urunuela et al 2002) and accumulation of products of ROS-mediated lipid peroxidation (Nonaka et al 1989b(Nonaka et al , 1990Guyan et al 1990; Schoenberg et al , 1995Tsai et al 1998;Rau et al 2000) and protein modification (Reinheckel et al 1998), with concomitant depletion of low molecular weight antioxidants (Neuschwander-Tetri et al 1994;Luthen et al 1995;Tsai et al 1998;Schulz et al 1999;Kruse et al 2001;Rau et al 2001;Rahman et al 2004). It was also confirmed by ESR spectroscopy using spin traps (Nonaka et al 1989a).…”

Microcirculatory Dysfunction in Acute Pancreatitis

“…On the other hand, inflammatory mediators have the potential to induce NO via the inducible NO synthase (iNOS) [142] and, thus, might induce an imbalance of ET in favor of NO. In line with this, a recent study could demonstrate increased expression of iNOS in necrotizing pancreatitis, which was reduced by radical scavengers and anti-adhesive strategies [143]. High local levels of NO may cause oxidant/cytotoxic effects due to reaction of NO with superoxide anion to form peroxynitrite with the subsequent formation of nitrogen dioxide and hydroxyl radical [136,144].…”

Protective effect of inducible nitric oxide synthase inhibitor on pancreas transplantation in rats

“…A study about severe acute pancreatitis has shown a positive correlation between serum NO level and the number of adherent leucocytes [8] . The expression of iNOS is correlated to changes in the pancreatic histomorphology [9][10][11][12] . The expression of iNOS during reperfusion following pancreatic ischaemia contributes significantly to the development of acute pancreatitis [13] .…”