Alanyl- glutamine down- regulates iNOS and TNF-α 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- α 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 ( group Ⅰ ), 0.2 mL of FK506 in a dose of 0.1 mg/kg ( group Ⅱ ) or 1.0 mg/kg (group Ⅲ), and orally high -dose FK506 (0.2 mL, 1.0 mg/kg) plus intraperitoneal injection of Ala -Gln (0.5 g/kg )(group Ⅳ ),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 - α 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 - α 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 - α 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 - α 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 - α expression.