ADHESIVE MUCOUS GEL LAYER AND MUCUS RELEASE AS INTESTINAL BARRIER IN RATS

Background: Although it has been reported that total parenteral nutrit ion induces an increased intestinal permeability and a decreased mucou s gel layer covering the intestinal epithelium, the role of mucous gel on intestinal permeability has not been well understood. We examined the in vivo effects of N-acetyl cysteine (NAC) as mucolytic agent and colchicine as suppressant of the mucus production on the intestinal tr ansmission of fluorescein isothiocyanate dextran 70,000 (FITC-dextran) . Methods: Rats were divided into four groups. In each group, FITC-dex tran (750 mg/kg) with or without NAC (3000 mg/kg) was injected into th e small intestinal lumen 3 hours after intraperitoneal injection of sa line or colchicine (Col, 10 mg/kg). Thirty minutes after injection of FITC-dextran, blood samples were taken from portal vein to analyze pla sma fluorescein concentration by fluorescence spectrometry. Samples of small intestine were sectioned in a cryostat for fluorescence microsc opy, and the identical sections were stained by periodic acid-Schiff r eaction. Results: Plasma FITC-dextran level in NAC group was higher th an that in control group (p <.01), that in Col+NAC group was higher th an that in Col group (p <.01) and that in Col + NAC group was higher t han that in NAC group (p <.05). The spaces between villi were filled w ith mucous gel in the control and Col groups, whereas those were not e ntirely filled with mucous gel in NAC and Col + NAC groups. FITC-dextr an and mucous gel showed complementary distribution in all rats. The v illous interstitial edema was recognized in NAC group and the villi we re disrupted in Col + NAC group. Conclusions: These results suggest th at intestinal permeability is possibly affected not only by the mucous gel covering the intestinal epithelium but also by mucus release from goblet cells of the small intestine.