AIM To investigate the modulatory effect of recombinantexpressed vasoactive intestinal peptide(VIP) analogue(rVIPa) on trinitrobenzene sulfonic acid(TNBS)-induced colitis in rats. METHODS Forty-eight rats were randomized into six groups: normal control group(Control), model control group(TNBS), ethanol treatment group(ETOH), and VIP treatment groups with different dosage(rVIPa_(1nmol), rVIPa_(2nmol), rVIPa_(4nmol)). Diarrhea and bloody stool were observed. Colonic damage was evaluated histologically. The levels of tumor necrosis factor-α( TNF-α), interleukin-10(Il-10), myeloperoxidase(MPO) and endotoxin in colonic tissue and serum were determined by enzyme-linked immunosorbent assay(ElISA). The expression of occludin, ZO-1, Toll-like receptor 4(TlR4),and nuclear factor-kappa B p65(NF-κBp65), IκBα, and p-IκBα were detected by Western blot. RESULTS Administration with 2 nmol rVIPa prevented TNBSinduced necrosis, hyperemia, swelling, inflammation, etc., pathologic changes observed in the inner surface of colon in experimental rats. Moreover, rVIPa significantly decreased colonic TNF-α level(P < 0.001), MPO activity(P < 0.001) and serum endotoxin level(P < 0.01), and remarkably increased colonic Il-10 content(P < 0.001) in rats with TNBS-induced colitis. Furthermore, compared to the TNBS-induced colitis group, 2 nmol rVIPa treatment up-regulated the levels of occludin(P < 0.05) and ZO-1(P < 0.05), NF-κB p65(P < 0.01) and IκBα(P < 0.001), and down-regulated the levels of TlR4. CONCLUSION rVIPa ameliorates TNBS-induced colonic injury and inflammation and effectively protected the intestinal mucosal barrier function in rats. The mechanism may be related to TlR4/NF-κB-mediated signaling pathway. rVIPa could be used as a new alternative therapy for intestinal inflammatory disorders.
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