[Therapeutic effects of muscovite on ulcerative colitis in rats]

To explore the efficacy of muscovite on iodoacetamide -induced ulcerative colitis in rats and elucidate its possible mechanism.

Ulcerative colitis was induced in female Sprague-Dawley (SD) rats by an intracolonic injection of iodoacetamide. A total of 48 rats were divided randomly(by the method of random digits table) into 6 groups: control group, model group, low-dose muscovite group (360 mg/kg), high-dose muscovite group (720 mg/kg), 5-aminosalicylie acid (5-ASA) group and muscovite plus 5-ASA group (combined treatment), and each group had 8 rats. The body weight, disease activity index (DAI), macroscopic damage and microscopic score of rats in each group were subsequently evaluated after dosing for 7 days. The protein levels of tumor necrosis factor-α (TNF-α), interleukin-8 (IL-8) and myeloperoxidase (MPO) activity were detected by enzyme-linked immunosorbent assay(ELISA) while the activity of nuclear facor(NF)-κB was determined by immunohistochemistry.One way ANOVA and rank-sum test were used.

After doing, body weight macroscopic damage, microscopic score, TNF-α concentration, MPO and NF-κB activity of rats in each group were all significantly correlated with the dose of muscovite (r = 0.573, -0.647, -0.569, -0.681, -0.811, -0.842, all P < 0.05). High-dose muscovite group had no significant difference with 5-ASA group in body weightt, DAI, macroscopic damage, microscopic score, IL-8 concentration, TNF-α concentration, MPO and NF-κB activities((166 ± 5) vs (167 ± 5) g, 0.33 (0.00, 1.17) vs 0.17 (0.00, 0.83), 2.50 (2.00, 4.00) vs 3.00 (2.00, 3.00), 3.00 (2.00, 3.00) vs 2.50 (2.00, 3.00), (109 ± 17) vs (111 ± 15) pg/ml, (166 ± 38) vs (155 ± 45) pg/ml, (52 ± 6) vs (49 ± 4) U/g, 7.39 ± 0.42 vs 7.41 ± 0.34, all P > 0.05). The MPO and NF-κB activities of combined treatment group were lower than those of 5-ASA group((40 ± 4) vs (49 ± 4) U/g, 4.67 ± 0.72 vs 7.41 ± 0.34, all P < 0.05). However, other indices showed no significant difference with 5-ASA group (all P > 0.05).

Rectal administration of muscovite ameliorates colonic inflammation of iodoacetamide-induced colitis. Its underlying mechanism is probably due to the regulation of inflammatory response. Muscovite may be a potential therapeutic agent for treatment of ulcerative colitis.