Antioxidant Therapy with N-Acetylcysteine Plus Mesalamine Accelerates Mucosal Healing in a Rodent Model of Colitis

The aims of this study were to examine the ability of the antioxidant N-acetylcysteine (NAC) and mesalamine (5-ASA) alone and in combination to affect TNBS-induced colitis in rat. Three days following induction of TNBS colitis rats were randomized to receive daily intracolonic treatment with NAC, 5-ASA, and NAC plus 5-ASA for 5 or 8 days. At the end of the treatment period macroscopic and microscopic colonic injuries were scored. Myeloperoxidase (MPO) activity and cytokine gene expression were measured in colonic tissues. Results indicated that treatment with NAC plus 5-ASA caused a significantly greater reduction in colonic injury than either agent alone. Furthermore, combination therapy inhibited significantly MPO activity and inflammatory cytokine gene expression in the distal colon of TNBS-treated animals. The beneficial effects of NAC plus 5-ASA on reduction of colonic injury and promotion of healing were most evident after 8 days of treatment.     

Small-Intestinal Manifestations of Dextran Sulfate Sodium Consumption in Rats and Assessment of the Effects of Lactobacillus fermentum BR11

The dextran sulfate sodium (DSS) colitis model has been utilized to screen for novel therapeutics for ulcerative colitis. Evidence suggests the small intestine may also be affected by DSS. We characterized the effects of DSS on the small intestine and assessed the potential for Lactobacillus fermentum BR11 to modify or normalize DSS-induced changes. Rats were allocated to three groups, Water + Vehicle, DSS + Vehicle, and DSS + L. fermentum BR11. BR11 was administered twice daily for 14 days. DSS (2%) was provided from days 7 to 14. Small-intestinal tissue was analyzed for sucrase activity, histology, and crypt cell proliferation. Increased ileum crypt depth and cell proliferation was observed in DSS-treated rats compared to controls (P < 0.05). BR11 normalized these parameters. While DSS predominantly induces colonic damage, minor morphological alterations were also detected in the distal small intestine. L. fermentum BR11 normalized these features.     

Tanshinone IIA Ameliorates Trinitrobenzene Sulfonic Acid (TNBS)-Induced Murine Colitis

Inflammatory bowel diseases are characterized by proinflammatory cytokines, oxidative stress, and tissue damage. Recently, tanshinone had been shown to act as an antioxidant, and to have anti-inflammatory bioactivity. The study was carried out to investigate the effect of tanshinone IIA on the inflammatory response of experimental colitis. Murine colitis was induced by trinitrobenzene sulfonic acid (TNBS). Ten or 20 mg tanshinone IIA was administrated to mice 4 h before the induction of colitis, and repeated daily until the mice were sacrificed. Colonic inflammation was examined by histological analysis, myeloperoxidase (MPO) activity, and the production of proinflammatory cytokines in colonic tissue. Activation of nuclear factor-kappa B was identified by western blot and immunohistochemistry, and oxidative stress was shown by glutathione (GSH) level in tissue. The mice with colitis treated by tanshinone IIA showed less tissue damage, lower MPO activity, less production of TNF-α and IL-1β, a higher level of GSH in colonic tissue, and downregulated activation of nuclear factor-kappa B in lamina propria mononuclear cells, compared with those of the untreated colitis group. Our data indicates that tanshinone IIA inhibits inflammatory response of colitis by downregulating the production of proinflammatory cytokines, and attenuating oxidative stress, which suggests that tanshinone IIA may be a new potential management for inflammatory bowel diseases.     

Curcumin Prevents the Development of Dextran Sulfate Sodium (DSS)-Induced Experimental Colitis

Curcumin is a phenolic natural product isolated from the rhizome of Curcuma longa (turmeric). We evaluated the effects of curcumin on the development of dextran sulfate sodium (DSS)-induced experimental colitis. BALB/c mice were fed a chow containing either 3.5% (wt/wt) DSS or 3.5% DSS + 2.0% (wt/wt) curcumin. The body weight loss was more apparent in DSS-treated mice than in DSS + curcumin-treated mice. The disease activity index, histological colitis score, and MPO activity were all significantly higher in DSS-treated mice than in DSS plus curcumin-treated mice. Microscopically, mucosal edema, cellular infiltration, and epithelial disruption were much more severe in DSS-treated mice than in DSS + curcumin-treated mice. In DSS + curcumin-treated mice, NF-κB activation was blocked in the mucosa. In conclusion, the development of DSS-induced colitis was significantly attenuated by curcumin. Being a nontoxic natural dietary product, curcumin could be useful in treatment of IBD patients.     

The Effect of Hypericum perforatum (St. John’s Wort) on Experimental Colitis in Rat

The aim of the present study was to investigate the effect of Hypericum perforatum (HP) on the inflammatory and immune response of colonic mucosa in rat with induced inflammatory bowel disease and that on various enzyme activities in blood and bowel tissue. Male Wistar albino rats were divided into three main groups: control, third day, and seventh day of colitis. Third-day and seventh-day groups were divided into four subgroups. Colitis was induced in all groups except the control group by 2,4,6-trinitrobenzene sulfonic acid (TNBS). The colitis group received saline; treatment groups received HP extract (50, 150, and 300 mg/kg/day, respectively). Glutathione (GSH), catalase (CAT), and malondialdehyde (MDA) activities in blood were measured. Catalase, myeloperoxidase (MPO), glutathione peroxidase (GSH-Px), glutathione reductase (GR), malondialdehyde, and nitric oxide (NO) activities were measured from tissue samples. Colonic damage was significantly reduced by HP extract. Macroscopic scoring of colonic damage significantly reduced in groups given HP extract compared with in the colitis group (P < 0.001). Blood catalase levels were reduced in the HP (150 mg/kg/day) compared with the colitis group (P < 0.01). Blood GSH levels significantly increased in groups treated with HP compared with control (P < 0.001) on the third and seventh day. Tissue GR levels reduced in the colitis and HP (50 mg/kg/day) groups compared with control (P < 0.05). Tissue MPO activity increased in the colitis and treatment groups compared with control (P < 0.007). GSH-Px levels increased in the colitis group compared with control at day 3 (P = 0.006). HP has a protective effect on TNBS-induced inflammatory bowel disease (IBD), probably due to an anti-inflammatory and antioxidant mechanism.     

The Effect of Melatonin on TNBS-Induced Colitis

Ulcerative colitis is a multifactorial inflammatory disease of the colon and rectum with an unknown etiology. The present study was undertaken to investigate the effect of melatonin administration on oxidative damage and apoptosis in 2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced colitis. Rats were divided into four groups as follows: Group 1 (n=8)—TNBS colitis; Group 2 (n=8)—melatonin, 10 mg/kg/day ip, for 15 days in addition to TNBS; Group 3 (n=8)—melatonin alone, 10 mg/kg/day ip, for 15 days; and Group 4 (n=8)—isotonic saline solution, 1ml/rat ip, for 15 days (sham control group). Colonic myeloperoxidase (MPO) activities, malondialdehyde (MDA) levels, and glutathione (GSH) levels are indicators of oxidative damage, while caspase-3 activities reveal the degree of apoptosis of the colonic tissue. In all TNBS-treated rats, colonic MPO activity and MDA levels were found to be increased significantly compared to those in the sham group. Colonic MPO activity and MDA levels were significantly lower in the melatonin treatment group compared to TNBS-treated rats. GSH levels of colonic tissues were found to be significantly lower in TNBS-treated rats compared to the sham group. Treatment with melatonin significantly increased GSH levels compared to those in TNBS-treated rats. Caspas-3 activity of colonic tissues was found to be significantly higher in TNBS-treated rats compared to the sham group. Treatment with melatonin significantly decreased caspase-3 activity compared to that in TNBS-treated rats. These results imply a reduction in mucosal damage due to anti-inflammatory and anti-apoptotic effects of melatonin.     

Protective action of NADPH oxidase inhibitors and role of NADPH oxidase in pathogenesis of colon inflammation in mice

AIM: To investigate the role of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase in colon epithelial cells in the pathogenesis of acute and chronic colon inflammation in a mouse model of dextran sulphate sodium (DSS)-induced colitis.METHODS: Balb/c mice were divided into three groups: 8 mice with acute DSS-induced colitis (3.5% DSS solution; 7 d), 8 mice with chronic DSS-induced colitis (3.5% DSS solution for 5 d + water for 6 d; 4 cycles; total: 44 d) and 12 mice without DSS supplementation as a control group. Primary colonic epithelial cells were isolated using chelation method. The cells were cultivated in the presence of mediators (lipopolysaccharide (LPS), apocynin or diphenyleneiodonium). Viability of cells was assessed by fluorescent microscopy. Production of reactive oxygen species (ROS) by the cells was measured fluorometrically using Amplex Red. Production of tumour necrosis factor-alpha (TNF-α) by the colonic epithelial cells was analysed by ELISA. Nox1 gene expression was assessed by real-time PCR.RESULTS: Our study showed that TNF-α level was increased in unstimulated primary colonic cells both in the acute and chronic colitis groups, whereas decreased viability, increased ROS production, and expression of Nox1 was characteristic only for chronic DSS colitis mice when compared to the controls. The stimulation by LPS increased ROS generation via NADPH oxidase and decreased cell viability in mice with acute colitis. Treatment with NADPH oxidase inhibitors increased cell viability and decreased the levels of ROS and TNF-α in the LPS-treated cells isolated from mice of both acute and chronic colitis groups.CONCLUSION: Our study revealed the importance of NADPH oxidase in the pathogenesis of both acute and chronic inflammation of the colon.     

The Role of Zinc and Metallothionein in the Dextran Sulfate Sodium-Induced Colitis Mouse Model

Zinc (Zn) and its binding protein metallothionien (MT) have been proposed to suppress the disease activity in ulcerative colitis. To determine the role of Zn and MT in the dextran sulfate sodium (DSS)-induced model of colitis in mice, a DSS dose-response study was conducted in male C57BL/6 wild-type (MT+/+) and MT-null (MT−/−) mice by supplementing 2%, 3%, and 4% DSS in the drinking water for 6 days. In the intervention study, colitis was induced with 2% DSS, Zn (24 mg/ml as ZnO) was gavaged (0.1 ml) daily, concurrent with DSS administration, and the disease activity index (DAI) was scored daily. Histology, MT levels, and myeloperoxidase (MPO) activity were determined. DAI was increased (P<0.05) by 16% and 21% with 3% and 4% concentrations of DSS, respectively, compared to 2%, evident after 5 days of DSS administration. MPO activity was increased in MT+/+ compared to MT−/− mice and those receiving DSS. Zn administration had a 50% (P<0.05) lower DAI compared to DSS alone. Zn partially prevented the distal colon of MT+/+ by 47% from DSS-induced damage compared to MT−/− mice. MT did not prevent DSS-induced colitis and Zn was partially effective in amelioration of DSS-induced colitis.     

NF-κB Activation Precedes Increases in mRNA Encoding Neurokinin-1 Receptor,Proinflammatory Cytokines,and Adhesion Molecules in Dextran Sulfate Sodium–Induced Colitis in Rats

Nuclear factor kappa B (NF-κ B) plays a key role in initiating inflammation associated with colitis. A systematic study was conducted in the rat DSS colitis model to determine the temporal relationship between NF-κ B activation and expression of substance P (SP), neurokinin-1 receptor (NK-1R), proinflammatory cytokines, and adhesion molecules. Rats were given 5% DSS in their water and sacrificed daily for 6 days. Colon tissue was collected for assessment of histological changes, NF-κ B activation, myeloperoxidase (MPO) activity, and expression of NK-1R, SP, TNFα, IL-1β, VCAM-1, ICAM-1, E-selectin, CINC-1, MIP-1α, and iNOS. NF-κ B activation increased, biphasically, on Day 1 and again on Days 4–6. The mRNA levels for ICAM-1, CINC-1, IL-1β, TNFα, VCAM-1, and NK-1R rose significantly (P< 0.05) by 2–4 days. Increased iNOS mRNA levels, MPO activity, and mucosal damage occurred on Day 6. These data demonstrate that NF-κ B activation substantially precedes the onset of physical disease signs and active inflammation.     

Protective Effect of Lactulose on Dextran Sulfate Sodium-Induced Colonic Inflammation in Rats

Promising results have recently been obtained with pre- and probiotic therapy in ulcerative colitis (UC). The prebiotic potential of lactulose is well established, but it has not yet been investigated in experimental colitis models. The purpose of the study was to examine the effect of lactulose on an UC model induced by 3% dextran sulfate sodium (DSS) solution added to drinking water for 7 days in male Wistar rats. Lactulose (300-1000 mg/kg) or 5-aminosalicylic acid (5-ASA; 150 mg/kg) was administered orally twice daily for 6 days. Colonic ulceration area, colon length, body weight changes, diarrhea/bloody feces, colonic mucosal myeloperoxidase activity (MPO), thiobarbituric acid reactive substances (TBARS), and histology were examined. Treatment of animals with DSS for 7 days resulted in severe colonic lesions accompanied by diarrhea, bloody feces, a decrese in body weight, shortening of the colon length, and an increase in MPO activity as well as TBARS, compared to normal rats. Lactulose treatment ameliorated DSS-induced colitis in a dose-dependent manner, and at 1000 mg/kg all of the parameters examined, except TBARS, were shown to improve significantly as compared to controls. Daily administration of 5-ASA also significantly reduced the severity of colonic lesions following DSS treatment. These results demonstrated the protective effect of lactulose in this rat colitis model and suggested that the background of this lactulose effect may be due to alterations of colonic microflora.     

Inhibitory Effects of Fermented Brown Rice on Induction of Acute Colitis by Dextran Sulfate Sodium in Rats

Although the pathogenic mechanisms of inflammatory bowel diseases are not fully understood, colonic microbiota may affect the induction of colonic inflammation, and some probiotics and prebiotics have been reported to suppress colitis. The inhibitory effects of brown rice fermented by Aspergillus oryzae (FBRA), a fiber-rich food, on the induction of acute colitis by dextran sulfate sodium (DSS) were examined. Feeding a 5% and 10% FBRA-containing diet significantly decreased the ulcer and erosion area in the rat colon stained with Alcian blue. In another experiment, 10% FBRA feeding decreased the ulcer index (percentage of the total length of ulcers in the full length of the colon) and colitis score, which were determined by macroscopic observation. It also decreased myeloperoxidase activity in the colonic mucosa. Viable cell numbers of Lactobacillus in the feces decreased after DSS administration and was reversely correlated with severity of colitis, while the cell number of Enterobacteriaceae increased after DSS treatment and was positively correlated with colitis severity. These results indicate that FBRA has a suppressive effect on the induction of colitis by DSS and suggest FBRA-mediated modification of colonic microbiota.     

Impaired nitrergic innervation in rat colitis induced by dextran sulfate sodium

BACKGROUND & AIMS: The pathophysiological role of neuronal nitric oxide synthase (nNOS) in colitis remains unknown. METHODS: We investigated colonic transit, nonadrenergic, noncholinergic (NANC) relaxation, nNOS activity, and nNOS synthesis in the myenteric plexus in dextran sulfate sodium (DSS)-induced colitis in rats. RESULTS: Oral administration of 5% DSS for 7 days induced predominant distal colitis and delayed colonic transit. In the proximal colon, carbachol-, sodium nitroprusside-, and electrical field stimulation (EFS)-induced responses were not different between control and DSS-treated rats. In the distal colon, EFS-evoked cholinergic contraction, NANC relaxation, and orphanin FQ-induced contraction were significantly impaired in DSS-treated rats compared with those in control rats, but carbachol- and sodium nitroprusside-induced responses remained intact in DSS-treated rats. The number of nNOS-immunopositive cells, catalytic activity of NOS, and nNOS synthesis in the colonic wall were significantly reduced in the distal colon of DSS-treated rats. In contrast, the number of PGP 9.5-immunopositive cells and PGP 9.5 synthesis in the colonic wall remained intact in the distal colon of DSS-treated rats. CONCLUSIONS: These results suggest that impaired NANC relaxation in the distal colon is associated with reduced activity and synthesis of nNOS in the myenteric plexus in DSS-induced colitis.     

Therapeutic effect of a hydroxynaphthoquinone fraction on dextran sulfate sodium-induced ulcerative colitis

AIM: To evaluate the therapeutic effect of hydroxynaphthoquinone mixture (HM) on dextran sulfate sodium (DSS)-induced colitis and explore the underlying mechanisms.METHODS: BALB/c mice received 3.5% DSS for 6 d to induce ulcerative colitis. Groups of mice were orally administered HM 3.5, 7 and 14 mg/kg and mesalazine 200 mg/kg per day for 7 d. During the experiment, clinical signs and body weight, stool consistency and visible fecal blood were monitored and recorded daily. A disease activity index score was calculated for each animal. At the conclusion of the experiment, the colonic histopathological lesions were evaluated. Myeloperoxidase (MPO) activity and tumor necrosis factor-α (TNF-α) levels were determined. Protein expression levels of TNF-α, nuclear factor-κB (NF-κB) p65, inhibitor of κB (IκB) and phosphorylation of IκB (p-IκB) were analyzed by Western blot analysis.RESULTS: Administration of 3.5% DSS for 6 d successfully induced acute colitis associated with soft stool, diarrhea, rectal bleeding, and colon shortening, as well as a loss of body weight. Administration of HM effectively attenuated the severity of colonic mucosa injury. For histopathological analysis, HM treatment improved histological alterations and lowered pathological scores compared with the DSS only group. This manifested as a reduction in the extent of colon injury and inflammatory cell infiltration, as well as the degree of mucosal destruction. In addition, HM at doses of 7 and 14 mg/kg significantly decreased MPO activity in colonic tissue (0.98 ± 0.22 U/g vs 1.32 ± 0.24 U/g, 0.89 ± 0.37 U/g vs 1.32 ± 0.24 U/g tissue, P < 0.05) and serum TNF-α levels (68.78 ± 7.34 ng/L vs 88.98 ± 17.79 ng/L, 64.13 ± 14.13 ng/L vs 88.98 ± 17.79 ng/L, P < 0.05). Furthermore, HM down-regulated the expression of TNF-α, NF-κB p65 and p-IκBα in colonic tissue while up-regulating IκBα protein expression. These results suggest that the significant anti-inflammatory effect of HM may be attributable to its inhibition of TNF-α production and NF-κB activation.CONCLUSION: HM had a favorable therapeutic effect on DSS-induced ulcerative colitis, supporting its further development and clinical application in inflammatory bowel disease.     

Intravenous glutathione prevents renal oxidative stress after coronary angiography more effectively than oral N-acetylcysteine

This study proposes the intravenous administration of glutathione (GSH) as a novel strategy to prevent contrast medium-induced renal oxidative stress. Renal oxidative stress is a critical cause of contrast-induced nephropathy (CIN). Recent reports have described that N-acetylcysteine (NAC) may prevent CIN by scavenging reactive oxygen species in the kidney. Twenty-one patients with reduced renal function who underwent coronary angiography (CAG) were equally assigned to the control, NAC and GSH (100 mg/min for 30 min before CAG) groups. CIN occurred in two patients, one in the control and the other in the NAC group. In the control group, the urinary lipid hydroperoxides (LOOHs) increased to 299.5 ± 94.4% of the baseline at 2 h after CAG (mean ± SE, p < 0.01). The increase in LOOHs was completely abolished in the GSH group (5.5 ± 8.8%, p = ns), but not in the NAC group (196.8 ± 81.3%, p < 0.05). In the control group, the serum GSH level fell by 9.4 ± 2.3% at 2 h after CAG (p < 0.01). The decrease was prevented in the GSH group (−1.8 ± 8.5%, p = ns), but not in the NAC group (−10.0 ± 3.3%, p < 0.05). The renal damage by contrast medium-induced oxidative stress occurs soon after CAG, and intravenous GSH is more effective in preventing the oxidative stress than oral NAC. This advantage may make GSH a potentially more effective therapeutic strategy against CIN.     

Acute Colitis Enhances Responsiveness of Lumbosacral Spinal Neurons to Colorectal Distension in Rats

Aim of this study was to examine excitability and responsiveness of lumbosacral spinal neurons to colorectal distension (CRD) in rats with colitis induced by dextran sulphate sodium (DSS). Extracellular potentials of single L6-S2 spinal neurons were recorded in pentobarbital anesthetized and paralyzed rats. Results showed that 40/154 (26%) and 53/156 (34%) neurons responded to noxious CRD (80 mmHg, 20 s) in DSS-treated and control animals, respectively. Neurons with long-lasting and low-threshold excitatory responses to CRD were more frequently encountered in DSS-treated than in control groups (P < 0.05). The mean maximal excitatory responses of neurons to noxious CRD in DSS-treated animals were significantly greater and the duration of responses was longer than those in control animals (P < 0.05). It was suggested that lumbosacral spinal neurons with colorectal input had increased excitability and responsiveness following colitis, which might play an important role in development of colonic hypersensitivity and viscerosomatic referred pain.     

Preventive Effect of Pentoxifylline on Acute Radiation Damage via Antioxidant and Anti-inflammatory Pathways

Purpose The aim of the present study was to investigate whether pentoxifylline (PTX) treatment could protect against induced acute radiation enteritis. Method Rats received 100 mg/kg/day PTX for 7 days before irradiation and continued on treatment for 3 days after irradiation. The intestinal myeloperoxidase (MPO) activities and malondialdehyde (MDA), glutathione (GSH), prostaglandin E2, and thromboxane B2 levels were determined. Terminal ileum tissue was evaluated for morphological changes. Also, nuclear factor κ (NF-κ), tumor necrosis factor-α (TNF-α), and intercellular adhesion molecule 1 (ICAM-1) expressions were analyzed with immunohistochemisty methods. Results PTX treatment was associated with increased GSH levels and decreased MPO activity and MDA, prostaglandin E2, and thromboxane B2 levels. Histopathologic examination showed that intestinal mucosal structure was preserved in the PTX-treated group while having significant decreases in NF-κB, TNF-a, and ICAM-1 expression. Conclusions PTX appears to have a protective effect against radiation damage. This protective effect is mediated in part by decreasing both inflammatory reactions and oxidative stress.