[Therapeutic effect of trace element on ulcerative colitis experimental study]

To produce a chronic UC model in rats, and study the therapeutic effects of trace elements on this UC model as well as the in possible mechanisms.

Male Wistar rats (100-150 g) were given drinking water containing 1.5% dextran sulfate sodium (DSS) to induced UC. Rats developed UC were divided into 4 groups randomly, selenium group (Se group, Natural Selenium Liquid 6 ml.d-1, containing selenium 60 micrograms); zinc plus selenium group (ZS group, every rat was given zinc sulfate 180 mg.kg-1.d-1 and selenium 60 micrograms.d-1), while dexamethasone (7 mg.kg-1.d-1) was used as positive control and 0.9% NS as placebo control. All rats received enema twice a day for 15 days. Endoscopic and histologic scoring were carried out for assessment of the therapeutic effect of trace elements. Mucosal SOD activity, MDA content, zinc and selenium content and peripheral blood NK activity were assessed.

The efficacy of ZS group was better than that of placebo control (P < 0.01), and there was no difference between ZS group and positive control (P > 0.05). An increased SOD activity and decreased MDA content were found after the combined administration of zinc and selenium. Zinc and selenium concentration of colonial mucosal were increased significantly, so did the NK activity of peripheral blood.

The combined therapy of zinc and selenium is effective for UC treatment, of which the possible mechanism may be involved, A) concentrating in local mucus; B) acting as scavengers of oxygen-free radicals, protecting cell membrane from peroxidation; C) improving the function of immunosurveillance system.