Sini-san improves duodenal tight junction integrity in a rat model of functional dyspepsia

BACKGROUND Recent reports have demonstrated that impaired barrier function and local microinflammation in the duodenal mucosa contribute to the pathogeneses of functional dyspepsia (FD). Thus, restoring normal barrier integrity becomes a potential therapeutic strategy in the treatment of FD. Sini-San (SNS) is a traditional Chinese prescription that exhibits therapeutic effects in FD, but the underlying mechanisms remain not well understood. METHODS FD rats were established by tail clamping method and the therapeutic effect of SNS was evaluated by measuring the visceral sensitivity and gastric compliance. Transepithelial electrical resistance (TEER) that reveals epithelial barrier integrity was measured by Ussing chamber. The expression of tight junction (TJ) proteins, occludin and claudin-1, in the duodenum was determined by Western blot and immunofluorescence. The amount of tumor necrosis factor alpha (TNF-α) and interferon gamma (INF-γ) in duodenal mucosa was detected by enzyme-linked immune sorbent assay (ELISA). The mRNA level of transient receptor potential vanilloid type 1 (TRPV1) was measured by quantitative real time-polymerase chain reaction (qPCR). RESULTS SNS could improve gastric compliance and attenuate visceral hypersensitivity (VH) in FD rats. TEER was decreased in FD rats, but treatment with SNS restored normal level of TEER and the expression of occludin and claudin-1 in FD rats. In addition, SNS administration ameliorated FD-associated increase in the production of TNF-α, IFN-γ and the expression of TRPV1. CONCLUSIONS The therapeutic effect of SNS on FD is at least partially through improvement of TJ integrity and attenuation of FD-associated low-grade inflammation in the duodenum. Our findings highlight the molecular basis of SNS-based treatment of FD in human patients.