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Antioxidative enzymes activity during gut inflammation and hyperbaric treatment in DSS-induced colitis in BALB/c mice

INTRODUCTION: ROS generated by the inflammatory cells during an immune response create oxidative stress considered as important factor contributing to the pathogenesis of inflammatory bowel disease. Hyperbaric oxygenation (HBO2) treatment frequently applied in medical practice increases tissue oxygen content and also leads to enhanced ROS production. Positive therapeutic effects of HBO2 have been attributed to its antioxidative and anti-inflammatory action. In the present study DSS-induced colitis has been employed in BALB/c mice as an experimental model of gut mucosa inflammation to investigate the effects of HBO2 on the antioxidative enzymes and hydrogen peroxide and peroxynitrite production during the colonic inflammation. METHODS: BALB/c mice at the age of 10-12 weeks were randomized into 4 groups (m=20-25g, n=5 mice/group): control mice, control mice undergoing HBO2, mice receiving dextran sodium sulfate (DSS) and DSS treated mice undergoing HBO2. In drinking water ad libitum for 7 consecutive days mice were drinking 5% w/v of DSS. HBO2 started at day 1 and was administered until the end of experiment (60 min/2.4 ATM, 2x/day, days 1-8). After last HBO2 session, mice were scarified by cervical dislocation and colon, mesenteric lymph node (MLN) and spleen were collected for antioxidative enzymes activity, and MLN and spleen for determination of H2O2 and peroxynitrite production (basal level and after PMA activation). Results are presented as mean±S.E.M. The study was approved by the Ethical Committee of the Faculty of Medicine University of Osijek (Croatia). RESULTS: HBO2 treatment per se in spleen induced increase of SOD activity (p=0.040 compared to CTRL). Mice with DSS-induced colitis had increased activity of SOD (p=0.012 compared to CTRL) in the colon, and reduced CAT activity in MLN and spleen (p=0.023 and p=0.032, respectively) compared to CTRL group. HBO2 treatment increased CAT (p=0.020) and GPx (p=0.001) activities in the spleens of the DSS+HBO2 group of mice. Basal H2O2 and ONOO- production in the MLN lymphocytes from the DSS+HBO2 group was increased compared to the CTRL group (p=0.033). PMA stimulation of MLN resulted in increased H2O2 and ONOO- production in CTRL (p=0.031) and DSS+HBO2 (p=0.012) groups. In the spleen, HBO2 increased H2O2 and ONOO- production in CTRL+HBO2 and DSS+HBO2 groups (p=0.004 and p=0.007 compared to the CTRL ; and p=0.005 and p=0.009 compared to the DSS group). Their production after PMA-induced activation was decreased in the CTRL+HBO2 group (p=0.018 compared to basal level). CONCLUSION: Results confirmed that HBO2 exerts an anti-inflammatory effect on DSS-induced colitis in mice, and this effect at least involves antioxidative enzymes activity regulation. Further studies are necessary to determine direct effect of HBO2 treatment on antioxidative enzymes function in DSS-induced colitis. Where applicable, the authors confirm that the experiments described here conform with the Physiological Society ethical requirements.

antioxidative enzymes; gut inflammation; hyperbaric treatment; DSS-induced colitis; BALB/c mice

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