DNBS-induced Colitis In Rats Research Articles

Discovery of a novel RIPK2 inhibitor for the treatment of inflammatory bowel disease

Nucleotide-binding oligomerization domain-containing protein 1 and 2 (NOD 1/2) are important cytosolic pattern recognition receptors that initiate host immune response. The dysregulation of NOD signaling is highly associated with inflammatory bowel disease (IBD) that needs novel treatment options. Receptor-interacting protein kinase 2 (RIPK2) is a critical mediator of NOD signaling and considered a promising therapeutic target for IBD treatment. However, there are currently no RIPK2 inhibitors available for clinical use. Here, we report the discovery and characterization of Zharp2-1 as a novel and potent RIPK2 inhibitor that effectively blocks RIPK2 kinase function and NOD-mediated NF-κB/MAPK activation in both human and mouse cell lines. Zharp2-1 exhibits significantly superior solubility compared to the non-prodrug form of the advanced RIPK2 inhibitor prodrug GSK2983559. The improved solubility combined with favorable in vitro metabolic stability translated to excellent in vivo pharmacokinetic profiles for Zharp2-1. In addition, Zharp2-1 demonstrates better effects than GSK2983559 in inhibiting the muramyl dipeptide (MDP)-induced production of pro-inflammatory cytokines in human peripheral blood mononuclear cells (PBMCs) and MDP-induced peritonitis in mice. Furthermore, Zharp2-1 markedly reduces Listeria monocytogenes infection-induced cytokines release in both human and mouse cells. Importantly, Zharp2-1 significantly ameliorates DNBS-induced colitis in rats and suppressed pro-inflammatory cytokine release in intestinal specimens from IBD patients. Collectively, our findings indicate that Zharp2-1 is a promising RIPK2 inhibitor with the potential to be further developed for IBD therapy.

Ethanolic extract from Lepidium virginicum L. ameliorates DNBS-induced colitis in rats

Ethnopharmacological relevanceLepidium virginicum L. (Brassicaceae) is a plant widely used in traditional Mexican medicine as an expectorant, diuretic, and as a remedy to treat diarrhea and dysentery, infection-derived gastroenteritis. However, there is no scientific study that validates its clinical use as an anti-inflammatory in the intestine. Aim of the studyThis study aimed to investigate the anti-inflammatory properties of the ethanolic extract of Lepidium virginicum L. (ELv) in an animal model of inflammatory bowel disease (IBD)-like colitis. Materials and methodsThe 2,4-dinitrobenzene sulfonic acid (DNBS) animal model of IBD was used. Colitis was induced by intrarectal instillation of 200 mg/kg of DNBS dissolved vehicle, 50% ethanol. Control rats only received the vehicle. Six hours posterior to DNBS administration, ELv (3, 30, or 100 mg/kg) was administered daily by gavage or intraperitoneal injection. The onset and course of the inflammatory response were monitored by assessing weight loss, stool consistency, and fecal blood. Colonic damage was evaluated by colon weight/length ratio, histopathology, colonic myeloperoxidase (MPO) activity, and gene expression of proinflammatory cytokines, including tumor necrosis factor-alpha (TNF-α), interleukin-1beta (IL-1β), chemokine C-X-C motif ligand 1 (CXCL-1), and interleukin-6 (IL-6). ResultsRats treated with DNBS displayed significant weight loss, diarrhea, fecal blood, colon shortening, a significant increase in immune cell infiltration and MPO activity, as well as increased proinflammatory cytokine expression. Intraperitoneal administration of ELv significantly reduced colon inflammation, whereas oral treatment proved to be ineffective. In fact, intraperitoneal ELv significantly attenuated the clinical manifestations of colitis, immune cell infiltration, MPO activity, and pro-inflammatory (CXCL-1, TNF-α, and IL-1β) gene expression in a dose-dependent manner. ConclusionTraditional medicine has employed ELv as a remedy for common infection-derived gastrointestinal symptoms; however, we hereby present the first published study validating its anti-inflammatory properties in the mitigation of DNBS-induced colitis.

5-[(3-Carboxy-4-hydroxyphenyl)diazenyl] nicotinic acid, an azo-linked mesalazine-nicotinic acid conjugate, is a colon-targeted mutual prodrug against dextran sulfate sodium-induced colitis in mice

We aimed to develop a 5-aminosalicylic acid (5-ASA, mesalazine)-based anti-colitic drug with higher efficacy than sulfasalazine (SSZ), a colon-targeted prodrug of 5-ASA, for the treatment of inflammatory bowel disease (IBD). To this end, we synthesized a colon-targeted mutual prodrug (ASA-azo-NA) consisting of 5-ASA and the GPR109A agonist nicotinic acid, 5-[(3-carboxy-4-hydroxyphenyl)diazenyl] nicotinic acid. In our previous study, oral gavage of ASA-azo-NA delivered 5-ASA and 5-aminonicotinic acid specifically to the large intestine in a 2,4-dinitrobenzene sulfonic acid (DNBS)-induced rat colitis model and ameliorated colonic damage and inflammation more effectively than oral SSZ. To increase the therapeutic convincibility of ASA-azo-NA for the treatment of IBD with multifactorial pathologies, the colon targetability and therapeutic activity of ASA-azo-NA were examined using a dextran sulfate sodium (DSS)-induced colitis mouse model with a different pathogenesis from that of DNBS-induced colitis in rats. ASA-azo-NA liberated 5-ASA in the cecal contents of mice while remaining stable in the small intestinal contents, with a cecal conversion rate and extent comparable to those of SSZ. Oral ASA-azo-NA and SSZ accumulated similar concentrations of 5-ASA in the cecum, indicating that ASA-azo-NA was delivered to and activated in the large intestine as efficiently as SSZ. In mice with DSS-induced colitis, oral ASA-azo-NA mitigated colonic damage and inflammation, as assessed using macroscopic and molecular indices, and was therapeutically superior to SSZ. ASA-azo-NA acted as a colon-targeted mutual prodrug against DSS-induced mouse colitis. Thus, ASA-azo-NA may be therapeutically applicable to patients with IBD who are resistant to SSZ treatment.

S3183 Effect of Azo Bonded 5-ASA and 4-APAA on DNBS-Induced Colitis in Rats

INTRODUCTION: Azo chemistry, enables drug delivery to the colon, where bacterial azo reductases can cleave the bond, liberating the two moieties. In all commercial IBD azo preparations, the only active moiety is 5-ASA, an anti-inflammatory agent. Delivering two different active moieties such as anti-inflammatory and an immunomodulator may improve efficacy. 4-aminophenylacetic acid (4-APAA), has been used in Japan for the past 10 years in the treatment of Rheumatoid Arthritis. It has an available amino group for azo bonding. 4-APAA is known to reduce TNF-α, IL-1β, MMP-1 production and to reduce the adhesion of T cells. We herein report the effect of azo bonded 5-ASA + 4-APAA on experimental colitis in rats. METHODS: Experimental colitis—on Day 0, a catheter was inserted rectally into the colon and the irritant, an ethanolic solution of 2,4 dinitrobenzenesulfonic acid (DNBS) was instilled at a volume of 0.5 mL. Concentration of DNBS was 60 mg/mL in 30% ethanol for a total dose of 30 mg DNBS. Animals—30 adult male Lewis rats (weighting 200–250 g) were divided into 5 groups of 6 animals each: (1) Vehicle; (2) Vehicle + DNBS; (3) 5-ASA 100 mg/kg/day + DNBS; (4) 4-APAA 99 mg/kg/day + DNBS; (5) Azo bonded 5-ASA + 4-APAA 199 mg/kg + DNBS. All groups received rectal bid doses of test compounds for the 4 days following induction of colitis. Animals were sacrificed on day 5 and animals were scored for the presence and severity of intestinal lesions (0 to 2 scale). Colon: body weight ratios were also determined. Statistics – t-test was used and P < 0.05 was deemed as significant. RESULTS: Compared to the vehicle/DNBS group, adhesion scores were reduced by 17%, 25%, and 38% in the 5-ASA, 4-APAA and azo bonded 5-ASA + 4-APAA groups respectively. The azo bonded 5-ASA + 4-APAA group was also better than the 5-ASA group. Compared to the vehicle/DNBS group, the average net colon to body weight ratio was reduced by 31.8%, 31.3 % and 31.1 % in the 5-ASA, 4-APAA and azo bonded 5-ASA + 4-APAA groups respectively. No significant difference was observed between the groups. CONCLUSION: The main findings of the present study are that rectally administered 4-APAA alone and azo bonded 5-ASA + 4-APAA are effective inhibitors of experimental colitis in a rat model and that this effect is of similar magnitude to the of 5-ASA. The azo bonded 5-ASA + 4-APAA also trended to better than each component separately, therefore may be a better alternative than single moiety azo preparations.Figure 1.: DNBS Colitis Adhesion Score.

PD123319, angiotensin II type II receptor antagonist, inhibits oxidative stress and inflammation in 2, 4-dinitrobenzene sulfonic acid-induced colitis in rat and ameliorates colonic contractility

Angiotensin II, the main effector of renin angiotensin system, plays an important role in the inflammatory process and most of its effects are mediated through the AT1 receptor activation. However, the knowledge about the AT2 receptor involvement in this process is still evolving. We previously found that in an experimental model of colitis, AT2 receptor activation can contribute to the impairment of the muscle contractility in vitro in the course of inflammation. Here, we investigated the potential alleviating effects of the in vivo treatment of PD123319 (1-[[4-(Dimethylamino)-3-methylphenyl]methyl]-5-(diphenylacetyl)-4,5,6,7- tetrahydro-1H-imidazo[4,5-c]pyridine-6-carboxylic acid ditrifluoroacetate), AT2 receptor antagonist, in 2,4-dinitrobenzene sulfonic acid (DNBS)-induced rat model of colitis. The effects of i.p PD123319 (0.3, 3 and 10 mg/kg) administration to rats subjected to intra-rectal DNBS instillation were investigated. The study revealed that the colon injury and the inflammatory signs were ameliorated by PD123319 when visualized by the histopathological examination. The colon shortening, myeloperoxidase activity, and colonic expression of IL-1β, IL-6 and iNOS were downregulated in a dose-dependent manner in DNBS-induced colitis rats treated with PD123319 and the anti-oxidant defense machinery was also improved. The mechanism of these beneficial effects was found in the ability of PD123319 to inhibit NF-κB activation induced by DNBS. The colonic contractility in inflamed tissues was also improved by PD123319 treatment. In conclusion, our data have demonstrated previously that undescribed proinflammatory effects for the AT2 receptors in DNBS-induced colitis in rats in which they are mediated likely by NF-κB activation and reactive oxygen species generation. Moreover, when the inflammatory process is mitigated by the AT2 receptor antagonist treatment, the smooth muscle is able to recover its functionality.

Intestinal Anti-Inflammatory Activity of the Aqueous Extract from Ipomoea asarifolia in DNBS-Induced Colitis in Rats.

Inflammatory bowel disease is triggered by an uncontrolled immune response associated with genetic, environmental, and intestinal microbiota imbalance. Ipomoea asarifolia (IA), popularly known as “salsa” or “brave salsa”, belongs to the Convolvulaceae family. The aim of this approach was to study the preventive effect of IA aqueous extract in 2,4-dinitrobenzene sulfonic acid (DNBS)-induced colitis in rats. Rats pretreated with IA extract or sulfasalazine (SSZ) received intracolonic instillation of DNBS in 50% ethanol (v/v). IA extract presented a protective effect against intestinal inflammation, with improvement in the disease activity index and macroscopic damage. IA or SSZ significantly reduced myeloperoxidase activity, and also down-regulation of the gene expression of JNK1, NF-κβ-p65, STAT3, and decreased levels of TNFα, IL-1β, and increased IL-10, associated with a significant improvement of oxidative stress, in addition to a reduction in MDA and an increase of glutathione in colonic tissue. The protective effect of the extract was also confirmed in histological evaluation, showing preservation of the colonic cytoarchitecture. Immunohistochemical analysis revealed down-regulation of NF-κβ-p65, iNOS, IL-17, and up-regulation of SOCs-1 and MUC-2. IA extract presents antioxidant and anti-inflammatory intestinal properties, and proved to be a potential application for preventing damage induced by DNBS.

A colon-specific prodrug of metoclopramide ameliorates colitis in an experimental rat model.

BackgroundWe examined whether metoclopramide (MCP), a modulator of dopamine and serotonin receptors, alleviated colitis and had synergistic effects when coadministered with 5-aminosalicylic acid (5-ASA) in an experimental model of colitis.MethodsMCP azo-linked to 5-ASA (5-[4-chloro-2-{2-(diethylamino)ethylcarbamoyl}– 1-methoxyphenyl]azosalicylic acid, MCP-azo-ASA) was synthesized, where 5-ASA was used as a colon-targeting carrier and an anti-colitic agent, and the ability of MCP-azo-ASA to target the colon in vitro and in vivo was evaluated.ResultsOur results indicate that MCP-azo-ASA was cleaved to MCP and 5-ASA in the cecal contents, but not in the contents of the small intestine. Oral gavage with equimolar concentrations of MCP-azo-ASA and sulfasalazine (SSZ, a colon-specific prodrug of 5-ASA widely used clinically) demonstrated that the two prodrugs delivered comparable amounts of 5-ASA to the cecum. MCP was barely detected in the blood after oral gavage with MCP-azo-ASA. In a rat model of 2,4-dinitrobenzene sulfonic acid hydrate (DNBS)-induced colitis, MCP-azo-ASA alleviated colonic damage in a dose-dependent manner. Moreover, MCP-azo-ASA reduced the concentrations of inflammatory mediators in the inflamed colon. At low equimolar doses, MCP-azo-ASA, but not SSZ, resulted in significant anti-colitic effects, which indicates that MCP has anti-colitic activity. MCP-azo-ASA had anti-colitic effects equal to those of SSZ at high equimolar doses.ConclusionThus, our results indicate that MCP-azo-ASA is a colon-specific prodrug of MCP. Targeted delivery of MCP to the colon ameliorated DNBS-induced colitis in rats, and we did not observe any synergistic effects of MCP after co-delivery with 5-ASA.

Preventive effects of guanosine on intestinal inflammation in 2, 4-dinitrobenzene sulfonic acid (DNBS)-induced colitis in rats.

Guanosine, a guanine-based purine, is an extracellular signaling molecule exerting anti-inflammatory and antioxidative effects in several in vivo and in vitro injury models. We aimed to investigate its protective effects on 2, 4-dinitrobenzene sulfonic acid (DNBS)-induced colitis in rat. Rats were divided into five groups and colitis was induced by intracolonic instillation of DNBS (15mg/rat). Guanosine (4 or 8mg/kg) was administered for 6days i.p. starting the day of the colitis induction. Body weight loss, stool consistency, colon weight/length, histological analysis, myeloperoxidase activity (MPO) and pro-inflammatory cytokine levels were assessed. Immunoblotting of nuclear factor-κB (NF-κB) p65 protein levels and detection of oxidative and nitrosative stress markers were also performed. Guanosine, in a dose-dependent manner, significantly ameliorated the severity of DNBS-induced colitis, reducing body weight loss and diarrhea incidence, preventing the DNBS-induced macroscopic and microscopic damage to the colonic mucosa, and the MPO increase. Guanosine treatment also lowered interleukin-1β, interleukin-6, and tumor necrosis factor-α mRNA levels. Importantly, guanosine in DNBS rats down-regulated the expression of NF-κB p65 and the levels of reactive oxygen species and nitrite. In conclusion, guanosine exerts beneficial effects in DNBS-induced colitis in rats, through modulation of colonic inflammation, downregulating of NFκB-mediated signaling.

DNBS/TNBS Colitis Models: Providing Insights Into Inflammatory Bowel Disease and Effects of Dietary Fat

Inflammatory Bowel Diseases (IBD), including Crohn's Disease and Ulcerative Colitis, have long been associated with a genetic basis, and more recently host immune responses to microbial and environmental agents. Dinitrobenzene sulfonic acid (DNBS)-induced colitis allows one to study the pathogenesis of IBD associated environmental triggers such as stress and diet, the effects of potential therapies, and the mechanisms underlying intestinal inflammation and mucosal injury. In this paper, we investigated the effects of dietary n-3 and n-6 fatty acids on the colonic mucosal inflammatory response to DNBS-induced colitis in rats. All rats were fed identical diets with the exception of different types of fatty acids [safflower oil (SO), canola oil (CO), or fish oil (FO)] for three weeks prior to exposure to intrarectal DNBS. Control rats given intrarectal ethanol continued gaining weight over the 5 day study, whereas, DNBS-treated rats fed lipid diets all lost weight with FO and CO fed rats demonstrating significant weight loss by 48 hr and rats fed SO by 72 hr. Weight gain resumed after 72 hr post DNBS, and by 5 days post DNBS, the FO group had a higher body weight than SO or CO groups. Colonic sections collected 5 days post DNBS-treatment showed focal ulceration, crypt destruction, goblet cell depletion, and mucosal infiltration of both acute and chronic inflammatory cells that differed in severity among diet groups. The SO fed group showed the most severe damage followed by the CO, and FO fed groups that showed the mildest degree of tissue injury. Similarly, colonic myeloperoxidase (MPO) activity, a marker of neutrophil activity was significantly higher in SO followed by CO fed rats, with FO fed rats having significantly lower MPO activity. These results demonstrate the use of DNBS-induced colitis, as outlined in this protocol, to determine the impact of diet in the pathogenesis of IBD.

Alleviation of antioxidant defense system by ozonized olive oil in DNBS-induced colitis in rats.

The aim of the study was to evaluate the potential protective effect of ozonized olive oil (OZO) in 2,4-dinitrobenzene sulphuric acid (DNBS) induced colitis in rats and to elucidate the role of some antioxidant defense system (superoxide dismutase “SOD,” glutathione peroxidase “GSH-Px,” and catalase “CAT”) in these effects. The physicochemical parameters including viscosity, peroxide, and acid values of olive oil and OZO were evaluated. The animals were divided into several groups and the colitis was induced in the rats by intracolonic instillation of DNBS at dose of 15 mg/rat. Olive oil (OO) at dose of 6 mg/kg and OZO at doses of 3 and 6 mg/kg was administered orally for 7 days, starting the day before induction of colitis. Our results showed that macroscopic and microscopic damage scores were significantly reduced in a dose response manner in rats pretreated with OZO only. In contrast, CAT, GSH-Px, and SOD activities were significantly increased in the distal colon of inflamed animals pretreated with OZO with respect to control group dose dependently. Results demonstrate that OZO pretreatment exerts protective effects in DNBS induced colitis in rats and provide evidence that the protective effects of OZO are mediated by stimulation of some antioxidant enzymes.

Protective effect of aqueous extract of Oroxylum indicum Linn. (root bark) against DNBS-induced colitis in rats

Objective:Aqueous root extract of Oroxylum indicum was evaluated in rats against dinitrobenzene sulfonic acid (DNBS) induced colitis.Materials and Methods:Rats were pre-treated orally for seven days and continued for four days after the induction of colitis with OIaq (100, 200, and 400 mg/kg) or vehicle. Colitis was induced by intracolonic instillation of 25 mg of DNBS per rat dissolved in 50% alcohol and 4 days later, the colonic mucosal damage was analyzed along with food intake, body weight, colon weight, spleen weight, histological damage, myeloperoxidase (MPO) activity, malondialdehyde (MDA) levels, reduced glutathione (GSH), and nitric oxide levels in colonic tissue homogenate.Results:Significant reduction in gross damage area, weight loss and increase in colonic and spleen weight were evident in test substance-pretreated animals’ dose dependently as compared to vehicle treated control. These effects were confirmed biochemically by a reduction in colonic myeloperoxidase activity, malondialdehyde levels, nitric oxide levels, and increase in reduced glutathione (GSH) levels. Furthermore, microscopic examination revealed diminution of inflammatory cell infiltration and submucosal edema in colon segments of rats treated with OIaq.Conclusion:The results demonstrate the protective effect of OIaq in the animal model of acute colitis possibly through an antioxidant, anti-lipoperoxidative or due to reduction in nitric oxide generation.

Effects of the Novel Non-Peptidyl Low Molecular Weight Radical Scavenger IAC in Different Models of Inflammation: A New Perspective in Anti-Inflammatory Therapy

The bis (1-hydroxy-2,2,6,6-tetramethyl-4-piperidinyl)-decandioate called IAC, is a new non-peptidyl low molecular weight radical scavenger able to give a fast reaction with the majority of radical species involved in the oxidative stress. This intrinsic property might be of particular interest in all the processes where it presents an over production of reactive oxygen/nitrogen species (ROS/RNS) such as inflammation. Indeed, it is well known that systemic inflammatory response is associated with the production of ROS, nitric oxide (NO), which in turn deplete the endogenous GSH, mediating cytotoxicity. It has been shown that IAC through its antioxidant activity, exerted a protective effect in vitro in islets isolated from type-2 diabetic patients, and in vivo in a non-obese diabetic mouse model and in DNBS-induced colitis in rats. The ability of IAC to protect brain from ischemia, suggests a possible use of the compound in broad range of inflammatory- related diseases. It is well known that the use of non steroidal anti-inflammatory drugs (NSAIDs) is associated with a broad spectrum of untoward side-effects such as gastrointestinal ulceration. The major pathogenetic element in the development of these effects is the depletion of prostaglandins (PGs) through inhibition of cyclooxygenase. The evidence that IAC protects gastric mucosa in an animal model of indomethacin-induced ulcer, through local increase of PGE2 levels and antioxidant activity, candidates this compound as a novel, promising, anti-inflammatory compound avoiding the major common untoward side-effects elicited by NSAID's.

The protective action of radix Astragalus membranaceus against hapten-induced colitis through modulation of cytokines

Astragalus membranaceus is a medicinal herb with potential immunomodulatory property, which has been used in treating colitis-related diarrhea. In the present investigation, we aimed to further explore its anti-inflammatory activity by studying the immunoregulatory mechanism of Astragalus root extract (Am) through different routes of administration in hapten-induced colitis. 2,4-Dinitrobenzene sulfonic acid (DNBS) was used to induce experimental colitis in Sprague–Dawley rats. Results have indicated that both oral and intracolonic Am treatments (administered twice daily for three consecutive days following colitis induction) exhibited significant protection against DNBS-induced colitis in rats, indicated by decreased colonic lesion area and histological damage score as well as amelioration of the elevated colonic myeloperoxidase activity. Western immunoblotting has revealed that oral Am could diminish the overexpression of tumor necrosis factor (TNF)-α and interleukin (IL)-1β, while concomitantly abolishing the inhibition of IL-10 expression in rats’ colon under colitis condition. On the other hand, intracolonic Am could only reduce TNF-α and interferon-γ overexpression. In summary, we have demonstrated that both oral and locally administered Am possess protective effects against experimental colitis through differential modulation of colonic cytokines. This study provides important new insights that may contribute to further development of Am as a novel therapeutic agent for treating colitis diseases.

Effects of the non-peptidyl low molecular weight radical scavenger IAC in DNBS-induced colitis in rats

Intestinal inflammation is accompanied by excessive production of reactive oxygen and nitrogen radical species because of the massive infiltration of polymorphonuclear and mononuclear leukocytes. Antioxidant compounds seem to protect against experimental colitis. Here we investigated the effects of the innovative non-peptidyl, low molecular weight radical scavenger bis(1-hydroxy-2,2,6,6-tetramethyl-4-piperidinyl)decandioate (IAC), which is highly reactive with most oxygen, nitrogen and carbon centred radicals and is easily distributed in cell membranes and intra-extra cellular compartments, in the DNBS model of colitis. Colitis was induced in male SD rats by intrarectal administration of DNBS (15 mg/rat). IAC (30 mg/kg b.w., hydrophilic or lipophilic form) was administered daily (orally or i.p.) starting from the day before the induction of colitis for 7 days (n=6–8 per group). Colonic damage was assessed by means of macroscopic and histological scores, myeloperoxidase activity (MPO) and TNF-α tissue levels. Colitis impaired body weight gain and markedly increased all inflammatory parameters. IAC significantly counteracted the reduction in body weight gain, decreased colonic damage and inflammation and TNF-α levels in DNBS-colitis. The antioxidant IAC significantly ameliorates experimental colitis in rats. This strengthens the notion that antioxidant compounds may have therapeutic potential in inflammatory bowel disease.

Protection from DNBS-induced colitis by the tachykinin NK 1 receptor antagonist SR140333 in rats

Inflammation is known to be associated with changes in tachykinin expression both in human and animal models: substance P and NK 1 receptor expression are increased in patients with inflammatory bowel disease, and similar changes are reported in experimental models of inflammation. We investigated the effect of the tachykinin NK 1 receptor antagonist SR140333 (10 mg/kg orally) on 2,4-dinitrobenzene sulfonic acid (DNBS)-induced colitis in rats. Colonic damage was assessed by means of macroscopic and microscopic scores, myeloperoxidase activity (MPO) and TNF-α tissue levels on day 6 after induction of colitis. An enzyme immunoassay technique was used to measure colonic substance P levels. DNBS administration impaired body weight gain and markedly increased all inflammatory parameters as well as colonic tissue levels of substance P. Treatment with SR140333 significantly counteracted the impairment in body weight gain, decreased macroscopic and histological scores and reduced colonic myeloperoxidase activity and TNF-α tissue levels. Colonic tissue levels of substance P were also reduced by SR140333, although this effect did not reach statistical significance. In conclusion, treatment with SR140333 protects from DNBS-induced colitis in rats. These results suggest a role for NK 1 receptors and substance P in the development of intestinal inflammation and indicate tachykinin receptors as a potential pharmacological target in the treatment of inflammatory bowel disease.