3-nitrotyrosine and Ileal-Diseases

Intestinal ischemia/reperfusion causes tissue hypoxia and damage, leading to the pathophysiology of inflammation. The aim of this study was to investigate the effects of glutamine on the tissue injury caused by ischemia/reperfusion of the gut. Ischemia/reperfusion injury of the intestine was caused by clamping both the superior mesenteric artery and the celiac trunk for 30 min followed by the release of the clamp allowing reperfusion for 1h. This procedure results in splanchnic artery occlusion-injury. Based on our findings we propose that the amino acid glutamine, administered 15 min before reperfusion at the dose of 1.5mg/kg, i.v. may be useful in the treatment of various ischemia and reperfusion diseases. The present study was performed in order to determine the pharmacological effects of glutamine ischemia/reperfusion-induced intestinal injury in rats. In particular, to gain a better insight into the mechanism(s) of action of glutamine, we evaluated the following endpoints of the inflammatory response: (1) histological damage; (2) neutrophil infiltration of the reperfused intestine (MPO activity); (3) NF-kappaB activation and cytokines production; (4) expression of ICAM-1 and P-selectin during reperfusion; (5) nitrotyrosine and poly-ADP-ribose formation; (6) pro-inflammatory cytokine production; (7) inducible nitric oxide synthase expression; (8) apoptosis as shown by TUNEL staining and (9) Bax/Bcl-2 expression.

Topics: Animals; Apoptosis; Cell Adhesion Molecules; Glutamine; I-kappa B Kinase; Ileal Diseases; Ileum; Male; Neutrophil Infiltration; NF-kappa B; Nitric Oxide Synthase Type II; Poly Adenosine Diphosphate Ribose; Protein Transport; Random Allocation; Rats; Rats, Sprague-Dawley; Reperfusion Injury; Splanchnic Circulation; Time Factors; Tyrosine

The aim of the present study was to investigate the protective effect of the pineal secretary product melatonin in a model of splanchnic artery occlusion shock (SAO). SAO shock was induced in rats by clamping both the superior mesenteric artery and the celiac trunk for 45 min, followed thereafter by release of the clamp (reperfusion). At 60 min after reperfusion, animals were sacrificed for tissue histological examination and biochemical studies. There was a marked increase in the oxidation of dihydrorhodamine 123 to rhodamine (a marker of peroxynitrite-induced oxidative processes) in the plasma of the SAO-shocked rats after reperfusion, but not during ischemia alone. Immunohistochemical examination demonstrated a marked increase in the immunoreactivity to nitrotyrosine, an index of nitrogen species such as peroxynitrite, in the necrotic ileum in shocked rats. SAO-shocked rats developed a significant increase of tissue myeloperoxidase and malondialdehyde activity, and marked histological injury to the distal ileum. SAO shock was also associated with a significant mortality (0% survival at 2 hr after reperfusion). Reperfused ileum tissue sections from SAO-shocked rats showed positive staining for P-selectin, which was mainly localized in the vascular endothelial cells. Ileum tissue sections obtained from SAO-shocked rats with anti-intercellular adhesion molecule (ICAM-1) antibody showed a diffuse staining. Melatonin (applied at 3 mg/kg, 5 min prior to reperfusion, followed by an infusion of 3 mg/kg per hr), significantly reduced ischemia reperfusion injury in the bowel as evaluated by histological examination. This prevented the infiltration of neutrophils into the reperfused intestine, is evidenced by reduced myeloperoxidase activity and reduced lipid peroxidation. This was evaluated by malondialdehyde activity which reduced the production of peroxynitrite during reperfusion, markedly reduced the intensity and degree of P-selectin and ICAM-1 in tissue section from SAO-shocked rats and improved their survival. Taken together, our results clearly demonstrate that melatonin treatment exerts a protective effect and part of this effect may be due to inhibition of the expression of adhesion molecule and peroxynitrite-related pathways and subsequent reduction of neutrophil-mediated cellular injury.

Topics: Animals; Chemotaxis, Leukocyte; Endothelium, Vascular; Free Radical Scavengers; Ileal Diseases; Immunoenzyme Techniques; Intercellular Adhesion Molecule-1; Male; Malondialdehyde; Melatonin; Mesenteric Artery, Superior; Neutrophils; Oxidative Stress; P-Selectin; Peroxidase; Rats; Rats, Sprague-Dawley; Reperfusion Injury; Splanchnic Circulation; Tyrosine