Alanyl-glutamine down-regulates iNOS and TNF-? expression in injured intestinal mucosa induced by oral FK506 / 中国病理生理杂志

ABSTRACT

AIM: To investigate the effects of alanyl-glutamine (Ala-Gln) on expression of iNOS and TNF-? in injured intestinal mucosa induced by oral tacrolimus(FK506). METHODS: Twenty-four BALB/c mice were randomized to receive orally 0.2 mL of normal saline solution ( groupⅠ), 0.2 mL of FK506 in a dose of 0.1 mg/kg (groupⅡ) or 1.0 mg/kg (groupⅢ), and orally high-dose FK506 (0.2 mL, 1.0 mg/kg) plus intraperitoneal injection of Ala-Gln (0.5 g/kg )(groupⅣ),respectively. Damages of intestinal mucosa were determined by pathological examination. Intestinal mucosal permeability was analysed by FITC-dextran fluorescence assay. Expression of iNOS and TNF-? in intestine was detected by RT-PCR and Western blotting.RESULTS: Severe damage on the villi and increased intestinal permeability were observed in high-dose FK506 treated mice according to scanning electron microscopy and FITC-dextran flux respectively. The erosion and increased intestinal permeability were significantly alleviated by Ala-Gln treatment. Transcription of iNOS mRNA and TNF-? mRNA, which was up-regulated in high-dose FK506 treated group, was also markedly down-regulated in mice combined with Ala-Gln-treatment. A significantly increased expression of iNOS and TNF-? protein was found in the high-dose FK506 treated mice, while small amounts of these proteins were identified in the Ala-Gln-treated group.CONCLUSION: FK506 could induce a significant impairment of intestinal mucosa morphologically, which might be associated with up-regulated expression of iNOS and TNF-? in small intestinal mucosa. Subsequently, the intestinal permeability is increased. Ala-Gln has a strong protective effect on FK506-induced intestinal barrier dysfunction, probably relates to the down-regulation of iNOS and TNF-? expression.