The protective effect of glutamine on endotoxemic intestinal injury and expression of heme oxygenase-1 in rats

Abstract

To investigate the protective effect of glutamine (Glu) pretreatment on intestinal injury induced by endotoxin and expression of heme oxygenase-1 (HO-1) in rats. Thirty-two male Sprague-Dawley (SD) rats were randomly divided into four groups (n=8 in each group): normal control group, model group, Glu group and Glu+zinc protoporphyrin (ZnPP) group. In model group, endotoxemia was produced by intraperitoneal injection of lipopolysaccharide (LPS, 10 mg/kg). In Glu group, the rats received intragastrically 1 g/kg of Glu 12 hours before LPS intraperitoneal injection. In Glu+ZnPP group, the rats received 1 g/kg of Glu by gavage 12 hours before LPS intraperitoneal injection and ZnPP 10 mmol/kg intravenously via tail vein 1 hour before LPS injection. The distal ileum was harvested in full thickness 12 hours after LPS injection. The myeloperoxidase (MPO) activity, tumor necrosis factor-α (TNF-α) and interleukin-10 (IL-10) in the intestine were determined, the pathologic changes were observed and expressed in Chiu grade. The expression of HO-1 was evaluated by immunohistochemistry method. Compared with normal control group, the Chiu grade, MPO activity, the content of TNF-α and IL-10 were significantly increased in model group [Chiu grade: 3.3±0.4 vs. 1.1±0.6, MPO activity (U/g): 0.40±0.08 vs. 0.26±0.07, TNF-α (ng/g): 25.2±6.9 vs. 6.5±2.8, IL-10 (ng/g): 27.6±10.2 vs. 5.7±2.9, all P<0.01], and the expression of HO-1 was decreased. Compared with model group, the Chiu grade, MPO activity, the content of TNF-α in Glu group were significantly decreased [Chiu grade: 1.6±0.5 vs. 3.3±0.4, MPO activity (U/g): 0.25±0.05 vs. 0.40±0.08, the content of TNF-α (ng/g): 13.4±3.2 vs. 25.2±6.9, all P<0.01], while the level of IL-10 (ng/g) elevated (47.3±5.5 vs. 27.6±10.2, P<0.01), and the expression of HO-1 was increased. There was no difference in above mentioned indexes between model group and Glu+ZnPP group. Glu pretreatment significantly ameliorates the expression of HO-1 of intestinal tissue induced by LPS in rats, and intestinal mucosa is protected with alleviation of inflammatory reaction in intestinal tract.