allopurinol and Colitis

Xanthine oxidase (XO) is one of the major enzymes to generate superoxide anion (O2(-)), that is frequently associated with various diseases involving reactive oxygen species (ROS). 4-Amino-6-hydroxypyrazolo[3,4-d]pyrimidine (AHPP) is a potent XO inhibitor showing therapeutic potential for oxidative inflammatory diseases. However its very poor aqueous solubility makes pharmaceutical application difficult. To overcome this drawback, we have successfully synthesized a water soluble polyethylene glycol (PEG) conjugate of AHPP (PEG-AHPP) that exhibited good water solubility, forming micelles in aqueous solution. In the present study, the in vivo pharmacokinetics of this PEG-AHPP was examined. Further its therapeutic potential was investigated in dextran sulfate sodium (DSS) induced mouse colitis model. Compared to parental AHPP, the plasma t1/2 of PEG-AHPP was increased remarkably from 3h to 14h, indicating macromolecular nature of AHPP in circulation. In the DSS induced colitis model, oral administration of 2% DSS in drinking water resulted in the progression of the colitis with diarrhea and hematochezia as well as shortening of the large bowel. Administration of PEG-AHPP intravenously (10mg/kg) or orally (20mg/kg) suppressed pathogenesis significantly; namely diarrhea was reduced markedly, and the length of large bowel returned to almost normal level. Pathological examination clearly revealed improvement of colonic ulcer or necrosis. Production of inflammatory cytokines, i.e., interleukin-6 and tumor necrosis factor (TNF)-α, was significantly increased in DSS-induced colitis mice. However, it was markedly suppressed by PEG-AHPP administration. Similar results were found when serum 8-hydroxydeoxyguanosine (8-OHdG) and thiobarbituric acid reactive substances (TBARS), that are the index of oxidative injury, were measured. PEG-AHPP thus may be a potential candidate drug for ROS-related diseases including inflammatory bowel disease.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Animals; Caco-2 Cells; Colitis; Colon; Cytokines; Deoxyguanosine; Dextran Sulfate; Female; Humans; Mice, Inbred ICR; Micelles; Oxypurinol; Polyethylene Glycols; Reactive Oxygen Species; Solubility; Thiobarbituric Acid Reactive Substances; Water; Xanthine Oxidase

Inflammatory bowel diseases are accompanied by severe motility disorders. The aim of our study was to investigate whether the blockade of peripheral N-methyl-D-aspartate (NMDA)-sensitive glutamate receptors (NMDA-Rs) alters motility changes in chemically induced acute colitis and how this modulation is accomplished.. The inflammatory and motility changes in 2,4,6-trinitrobenzenesulfonic acid (TNBS)-induced colitis were studied in anaesthetized Wistar rats following treatment with the natural NMDA-R antagonist kynurenic acid (KynA) or SZR-72, a blood-brain barrier-permeable synthetic KynA analogue. The macrohaemodynamics, serosal microcirculation (visualized by intravital videomicroscopy), plasma levels of tumour necrosis factor alpha (TNF-alpha), inflammatory enzyme activities (xanthine oxidoreductase (XOR), myeloperoxidase (MPO) and nitric oxide synthase (NOS)), and colonic motility (with a strain-gauge technique) were evaluated 17 h after colitis induction and compared with the control conditions.. The TNBS enema induced a systemic hyperdynamic circulatory reaction, increased the serosal capillary blood flow, significantly elevated the mucosal XOR, MPO and NOS activities and augmented the colonic motility relative to the controls. The NMDA-R antagonist treatment with KynA or SZR-72 significantly reduced the XOR, NOS and MPO activities, decreased the motility and increased the tone of the colon.. These data demonstrate a potential modulatory mechanism of NMDA-R in altered colonic motility in TNBS colitis. Inhibition of the enteric NMDA-Rs may provide a therapeutic option via which to influence intestinal hypermotility, microcirculatory changes and inflammatory activation simultaneously.

Topics: Analysis of Variance; Animals; Blood Pressure; Colitis; Colon; Disease Models, Animal; Excitatory Amino Acid Antagonists; Gastrointestinal Motility; Inflammation; Kynurenic Acid; Male; Nitric Oxide Synthase; Peroxidase; Random Allocation; Rats; Rats, Wistar; Receptors, N-Methyl-D-Aspartate; Time Factors; Trinitrobenzenesulfonic Acid; Tumor Necrosis Factor-alpha; Xanthine Oxidase

To investigate the protective effects of Astragalus membranaceus (Am) against hapten-induced colitis in male Sprague-Dawley rats as well as its underlying mechanism.. Experimental colitis was induced in rats by enema administration of 2,4-dinitrobenzene sulfonic acid (DNBS). Rats were either pretreated with Am extract (2 or 4 g/kg, p.o. once daily) starting from 10 d before DNBS enema, or received Am post-treatment (2 or 4 g/kg, p.o. twice daily) on the three consecutive days following DNBS administration. Colonic lesion area and histological damage were determined, while the activities of myeloperoxidase (MPO) and xanthine oxidase, as well as reduced glutathione (GSH) content were measured in the excised colonic tissues. Besides, protein expression of inducible nitrite oxide synthase (iNOS), intercellular adhesion molecule-1 (ICAM-1) and P-selectin was also detected by Western blot analysis.. Our findings had shown that both macroscopic lesion area and histological colonic damage induced by DNBS were significantly reduced by both Am pre- and post-treatments. These were accompanied by attenuation of the elevated colonic MPO activity and downregulation of the iNOS, P-selectin, and ICAM-1 protein expression. Besides, deprivation of colonic GSH level under colitis condition was also preserved.. These results demonstrate that Am possesses both preventive and therapeutic potential in experimental colitis. The anti-inflammatory actions involve anti-oxidation along with inhibition of adhesion molecule synthesis in the colonic tissues.

Topics: Animals; Astragalus propinquus; Colitis; Colon; Dinitrofluorobenzene; Glutathione; Humans; Inflammatory Bowel Diseases; Intercellular Adhesion Molecule-1; Male; Medicine, Chinese Traditional; Nitric Oxide Synthase Type II; Oxidation-Reduction; P-Selectin; Peroxidase; Phytotherapy; Plant Extracts; Rats; Rats, Sprague-Dawley; Xanthine Oxidase

Many plants contain significant amounts of 4-coumaric acid (4CA), a compound with antioxidant properties in vitro and in vivo. The aim of this study was to assess the effects of 4CA pretreatment on DNA oxidative stress induced by intestinal inflammation in rodents.. 4CA (50 mg/kg) was administered to rats for 14 days mixed in the diet. Colitis was induced on days 13 and 14 by administering 6% (w/v) dextran sodium sulphate (DSS) in the drinking water.. In the colon mucosa, DSS treatment increased myeloperoxidase activity (P < 0.05), oxidative DNA damage (P < 0.01), and cyclooxygenase-2 (COX-2) expression (P < 0.01) and reduced superoxide dismutase-2 (SOD-2) expression (P < 0.05). It was found that treatment with 4CA prior to DSS-induced inflammation reduced oxidative DNA damage (P < 0.01), COX-2 over-expression (P < 0.01) and restored SOD-2 gene expression to control levels. Similar effects were observed with nimesulide administered p.o. (5 mg/kg, 1 day before and during DSS treatment). PGE levels in plasma and colon mucosa were increased by DSS treatment and this effect was inhibited by pretreatment with 4-CA (P < 0.01).. Mild acute intestinal inflammation induced by DSS can be inhibited by 4-CA and this action is associated with the suppression of COX-2 expression and activity.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Animals; Antioxidants; Colitis; Coumaric Acids; Cyclooxygenase 2; Deoxyguanosine; Dextran Sulfate; Dinoprostone; DNA Damage; Glutathione; Intestinal Mucosa; Male; Oxidative Stress; Peroxidase; Plant Extracts; Propionates; Prostaglandin-Endoperoxide Synthases; Rats; Rats, Inbred F344; Superoxide Dismutase; Xanthine Oxidase

Reactive oxygen metabolites are potent inflammatory mediators that may be involved in tissue injury in inflammatory bowel disease. To evaluate their role in inflammatory bowel disease, we investigated the effects of lowering the activities of reactive oxygen metabolites in experimental colitis induced by intracolonic administration of acetic acid in rats. Intracolonic administration of 5% acetic acid caused severe inflammation (mean (SEM) inflammatory score was 24.3 (0.7) of a maximum score of 32). Acetic acid at 2.5% produced moderate inflammation (score = 17 (1.4) v 4.0 (0.5) in control rats). This lower dose was used for subsequent experiments. Specific superoxide anion scavenger methoxypolyethylene glycol:superoxide dismutase, and reactive oxygen metabolites scavenger, sulfasalazine, significantly decreased the severity of inflammation (scores: 8 (4.4) and 9.8 (2.2) respectively). The xanthine oxidase inhibitors, tungsten and pterin aldehyde, failed to improve inflammation but another xanthine oxidase inhibitor, allopurinol, a compound with known superoxide anion scavenging effect, did limit the inflammation (10(2)). Inhibition of hydroxyl radical production by deferoxamine or lowering hydroxyl radical values by a scavenger, dimethyl sulfoxide, did not affect the severity of inflammation. These data suggest: (1) that reactive oxygen metabolites play an important role in experimental colitis, (2) that the xanthine oxidase pathway is not a major source of reactive oxygen metabolites in colitis, and (3) that tissue injury in experimental colitis is not caused by generation of hydroxyl radicals.

Topics: Animals; Colitis; Female; Free Radicals; Hydroxides; Hydroxyl Radical; Oxygen; Rats; Superoxides; Xanthine Oxidase