Colonic Inducible Nitric Oxide Synthase Research Articles

Piperine, a functional food alkaloid, exhibits inhibitory potential against TNBS-induced colitis via the inhibition of IκB-α/NF-κB and induces tight junction protein (claudin-1, occludin, and ZO-1) signaling pathway in experimental mice

Inflammatory bowel disease is a chronic immunoinflammatory disease of the gastrointestinal tract. Piperine, an alkaloid, has been reported to possess antioxidant, anti-inflammatory, antiapoptotic, and antiulcer potential. To elucidate the plausible mechanisms of action of piperine on experimental trinitrobenzenesufonic acid (TNBS)-induced colitis by assessing various biochemical, molecular, histological, and ultrastructural modifications. Colitis was induced in male Sprague-Dawley rats via intrarectal instillation of TNBS. Then, the rats were treated with piperine (10, 20, and 40 mg/kg, p.o.) for 14 days. TNBS induced significant (p < 0.05) colonic damage, which was assessed by disease activity index, macroscopic score, and stool consistency. The administration of piperine (20 and 40 mg/kg) significantly inhibited (p < 0.05) these damages. Treatments with piperine (20 and 40 mg/kg) notably inhibited (p < 0.05) the TNBS-induced elevation of oxido-nitrosative stress (superoxide dismutase, glutathione, malondialdehyde, and nitric oxide), 5-hydroxytryptamine, and hydroxyproline content in the colon. Furthermore, colonic inducible nitric oxide synthase (iNOs), tumor necrosis factor-alpha (TNF-α), interleukin (IL)-1β, IL-6, interferon-gamma, and cyclooxygenase-2 (COX-2) messenger RNA (mRNA) expressions were upregulated after TNBS instillation and piperine (20 and 40 mg/kg) significantly attenuated (p < 0.05) these elevated mRNA expressions. TNBS decreased the expressions of tight junction (TJ) protein (claudin-1, occludin, and zonula occludens-1 (ZO-1)) and increased the expressions of proapoptotic (caspase-1) protein. These expressions were markedly inhibited (p < 0.05) by piperine treatment. Histological and ultrastructural studies of transmission electron microscopy suggested that piperine significantly ameliorated (p < 0.05) TNBS-induced colonic aberrations. Piperine ameliorated the progression of TNBS-induced colitis by modulating the nuclear factor of kappa light polypeptide gene enhancer in B-cells inhibitor-alpha/nuclear factor-kappa B signaling pathway, thus inhibiting the overexpression of proinflammatory cytokines (TNF-α and IL's), COX-2, iNOs, oxido-nitrosative stress, and proapoptotic proteins (caspase-1) that may improve the expression of TJ protein (claudin-1, occludin, and ZO-1).

Comparative Efficacy of Chitosan, Pectin Based Mesalamine Colon Targeted Drug Delivery Systems on TNBS-induced IBD Model Rats

A number of natural polymer-based drug delivery systems targeting the colon are reported for different applications. Most of the research is based on the class of natural polymers such as polysaccharides. This study compares the anti-inflammatory effect of different polysaccharide based tablets on IBD when a drug carrier is targeted to the colon as matrix and coated systems. The TNBS induced IBD Wistar rats were used as a model for the study. The microscopic and macroscopic parameters were studied in detail. Almost all the important IBD parameters were reported in this work. The results demonstrated that the polysaccharides are efficient in carrying the drugs to the colon. Reduction in the level of ulcer index (UI), Myeloperoxidase (MPO), and Malondialdehyde MDA, confirmed the inhibitory activity on the development of Reactive oxygen species (ROS). The increased level of Tumor necrosis factor (TNFα) an expression of colonic inducible nitric oxide synthase (iNOS) was lowered in treatments as compared to TNBS control. The different polymer-based mesalamine (DPBM) confirmed the efficient anti- inflammatory activity on IBD induced rats. The increased level of glutathione (GSH), and superoxide dismutase (SOD) also confirmed the effective anti-inflammatory effect. A significant decrease in the ulcer score and ulcer area was reported. The investigation revealed that chitosan is superior to pectin in IBD treatment likewise polysaccharide-based matrix systems are superior to the coated system.

Saccharomyces Boulardii Ameliorates Trinitrobenzenesulphonic Acid-Induced Experimental Colitis in Rats: Attenuation of Pro-Inflammatory Gene Expression

Saccharomyces Boulardii Ameliorates Trinitrobenzenesulphonic Acid-Induced Experimental Colitis in Rats: Attenuation of Pro-Inflammatory Gene Expression Sang Kil Lee, Hyo Jong Kim, Sung Gil Chi, Yoon Wha Kim Objectives: Saccharomyces boulardii (S. boulardii) is a nonpathogenic yeast used in the treatment of Clostridium difficile diarrhea and colitis. Recently S. boulardii was known to be beneficial in the treatment of inflammatory bowel disease. We have reported that S. boulardii reduces response of human colon cells to pro-inflammatory cytokines. The aim of this study was to further evaluate the effect of S. boulardii in the rats with trinitrobenzenesulphonic acid (TNBS) induced colitis. Methods: Rats were divided into three groups; Group 1 rats (untreated) were exposed only to TNBS (30mg) dissolved in 50% ethanol; Group 2 rats were exposed to TNBS and were then given lyophilized S. boulardii (10 mg suspended in 0.5 ml saline) twice a day by orogastric intubation for 7 days. Group 3 rats served as controls. Different biochemical markers of colonic inflammation were assayed by RT-PCR: interleukin-1b, interleukin-6, interleukin-8, tumor necrosis factor-a, and colonic inducible nitric oxide synthase expression. Macroscopic and microscopic findings of the colon were compared after sacrifice of the rats. Results: Intrarectal administration of TNBS dramatically induced the weight loss, colonic damage, and mucosal ulceration. Administration of S. boulardii attenuated TNBS-induced body weight loss and mortality (P ! 0.05, respectively), but did not improved colitis histologic score. Furthermore administration of S. boulardii significantly suppressed expressions of interleukin-1b, interleukin-6, interleukin-8, tumor necrosis factor-a, and colonic inducible nitric oxide synthase (p ! 0.01, respectively). Conclusions: These results suggest that S. bouladii down-regulates the expression of proinflammatory cytokines in the rats with TNBS induced colitis.

Preventative Effects of Lactulose in the Trinitrobenzenesulphonic Acid Model of Rat Colitis

Lactulose is a drug used as a laxative that has been shown to promote the growth of lactobacilli and bifidobacteria, acting as a prebiotic and with a potential beneficial effect in inflammatory bowel disease. The present study describes the preventive antiinflammatory activity of lactulose in the trinitrobenzenesulphonic acid (TNBS) model of rat colitis. Rats were rendered colitic by a colonic instillation of 10 mg of TNBS dissolved in 0.25 mL of 50% ethanol. One group of colitic rats received lactulose, which was incorporated in the drinking water (2.5% wt/vol) for 2 weeks before TNBS instillation, and colonic damage was evaluated 1 week after colitis induction. Different biochemical markers of colonic inflammation were assayed: myeloperoxidase activity, glutathione content, tumor necrosis factor alpha, leukotriene B4 levels, and colonic inducible nitric oxide synthase expression. In addition, bacterial counts (for lactobacilli and bifidobacteria) were performed in colonic contents from colitic rats. The results show that lactulose exerted a preventive antiinflammatory effect in this model of rat colitis, as evidenced by a significant reduction of myeloperoxidase activity and by a decrease of both colonic tumor necrosis factor alpha and leukotriene B4 production. This effect was also characterized by an inhibition of colonic inducible nitric oxide synthase expression, which is unregulated as a consequence of the inflammatory status. This beneficial effect was associated with increased levels of lactobacilli and bifidobacteria species in colonic contents in comparison with untreated colitic rats. In conclusion, the intestinal antiinflammatory effect of lactulose could be related to its prebiotic properties, supporting its potential use in human inflammatory bowel disease.

Time-dependent actions of nitric oxide synthase inhibition on colonic inflammation induced by trinitrobenzene sulphonic acid in rats

The time-dependent actions following pretreatment or delayed administration of the nitric oxide (NO) synthase inhibitor, NG-nitro-l-arginine methyl ester (l-NAME) on colonic inflammation and inducible NO synthase activity following the intrarectal administration of trinitrobenzene sulphonic acid (TNBS) were evaluated in the rat. Intracolonic instillation of TNBS (30 mg in 0.25 ml of 50% ethanol) led to macroscopic injury, an increase of mucosal myeloperoxidase activity and the expression of the Ca2+-independent inducible NO synthase over 8 days. The inflammatory response following TNBS reached maximum levels between 12 and 72 h and then it declined until 14 days. Oral administration of l-NAME (25 mg kg−1 per 24 h in the drinking water) 2 days before TNBS augmented macroscopic damage and increased colonic inducible NO synthase activity 6, 12, 24 and 72 h after TNBS administration. In contrast, when l-NAME was administered 6 h after TNBS instillation, at time of expression of inducible NO synthase, the macroscopic lesions were reduced, as well as the enhanced inducible NO synthase activity, determined, over 72 h. Delayed (6 h after TNBS) administration of l-NAME also attenuated the colonic myeloperoxidase activity provoked by TNBS, after 24 h. This activity was not affected by pretreatment (2 days before TNBS) with l-NAME. These findings indicate that the timing of administration of non-selective NO synthase inhibitors such as l-NAME, in models of colitis is critical to the eventual outcome. Thus, pretreatment with l-NAME, which will inhibit constitutive NO synthase, exacerbates the subsequent damage following challenge. In contrast, delayed administration of l-NAME at the time of inducible NO synthase expression, has a beneficial action on the colonic injury and inflammation.