Relationship between Visceral Sensitivity and Tryptophan Metabolic Pathway in Patients with Diarrhea-predominant Irritable Bowel Syndrome / 胃肠病学

ABSTRACT

Background:Tryptophan(TRP)is an essential amino acid,and can produce 5-hydroxytryptamine(5-HT)via 5-HT signal pathway and kynurenine( KYN)metabolic pathway under the catalysis of enzyme,thereby participating in the pathogenesis of visceral hypersensitivity in diarrhea-predominant irritable bowel syndrome(IBS-D). Aims:To investigate the relationship between visceral sensitivity and TRP metabolic pathway in patients with IBS-D. Methods:Thirty patients with IBS-D and 30 healthy controls from June 2012 to January 2014 at Guangdong Provincial TCM Hospital were enrolled. Score of gastrointestinal symptom rating scale( GSRS)was evaluated. Visceral sensitivity was measured by anorectal manometry. RT-PCR and Western blotting were used to detect mRNA and protein expressions of colon mucosal IDo, respectively. Serum 5-HT,5-HIAA,TRP,IDo,KYN,KYNA concentrations and IDo activity,KAT activity were determined by high performance liquid chromatography assay. Results:Compared with control group,GSRS score was significantly increased(P < 0. 05),initial perception threshold,defecation threshold,pain threshold were significantly decreased(P < 0. 05),anorectal constriction pressure was significantly increased( P < 0. 05),serum 5-HT,5-HIAA concentrations were significantly increased(P < 0. 05),mRNA and protein expressions of IDo were significantly increased (P < 0. 05),serum KYN was significantly increased(P < 0. 05),KYNA was significantly decreased(P < 0. 01),IDo activity was significantly incseased(P < 0. 01),and KAT activity was significantly decreased in IBS-D group(P < 0. 01). Correlation analysis showed that initial perception threshold,defecation threshold,pain threshold and anorectal constriction pressure were correlated with 5-HT,5-HIAA,TRP,KYN,KYNA,IDo activity and KAT activity in patients with IBS-D (P < 0. 05). Conclusions:TRP metabolic pathway is correlated with visceral hypersensitivity in patients with IBS-D.