Changes Of Neuropeptide Y In TNBS-tnduced Ibd Rat Model And It’s Mechanisms In Regulating Macrophage And Intestine Barrier Function

Neuropeptide Y (NPY) is a36-amino acid peptide which is widely distributed inthe central and peripheral nervous system. It contributes to a vast number ofphysiological processes including modulates anxiety, appetite, blood pressure andnociception. NPY and it’s receptors have also been implicated in several humandiseases including obesity, alcoholism, depression and coronary artery disease whichsupport the hypothesis that NPY-Y receptor system are worthwhile targets for thetherapy of such diseases.Infammatory bowel diseases (IBDs) are a group of infammatory disorders of thegastrointestinal tract characterized by an abnormal immune response to antigens ofthe intestinal content that leads to a persistent infammatory state. The exact cause ofIBD is still unknown. Epithelial barrier function and inflammation dysfunction aretwo major contributors to the pathogenesis of intestinal disease; however, muchremains unknown about how these two processes contribute independently to IBDinitiation.In order to verify the changes and the effect of NPY in IBD, IBD rat modelswere established by rectal infusion of TNBS, mRNA levels of NPY and Y1receptorin different tissues were quantified by real-time PCR, the concentration of NPY incerebrospinal fluid and serum were evaluated by ELISA at different time after rectalinfusion; in order to investigate the role of NPY on macrophages activation, mouseperitoneal macrophages were cultured with NPY and/or LPS, iNOS, COX-2, TNF-α,IL-1β and IL-6were measured by real time PCR and ELISA or western blot afterincubated with NPY and BIBP3226in the presence or absence of LPS; the effects ofNPY on TEER and TJs expression were quantified in Caco2cell lines. MAPKs andNF-κB signaling pathway were also detected.Our results showed that NPY and Y1receptor mRNA were highly detected in thehypothalamus, spleen and peripheral blood lymphocyte in the pathogenesis of IBD rat model, and the lowest mRNA level of NPY and Y1receptor were detected in thecolon tissue and thymus. Remarkably, NPY and Y1changed markedly at day3to7post rectal infusion. How ever, their mRNA levels began to gradually trended towardsnormal levels from day14with the recovery of symptoms, the concerntration ofNPY in cerebrospinal fluid and serum were significantly reduced at day7. NPYsignificantly reduced LPS-induced iNOS, IL-1β, IL-6and TNF-α mRNA expressionin mouse peritoneal macrophages as same as protein levels in cell supernatants.Mechanism involved in the process including activation of Y1receptor resulting ininhibition on the activation of NF-κB. In addition, NPY significantly reducetransepithelial electrical resistance in Caco2cell lines and inhibite the expression ofclaudin1, claudin3and occluding, while promote the expression of claudin2. Y1receptor, ERK pathway and Y2receptor NF-κB pathway may be involved in theseprocess.