Sulfasalazine or enteral diets containing fish oil or oligosaccharides attenuate chronic colitis in rats

Recent studies have suggested that n‐3 fatty acids from fish oil (FO) as well as short‐chain fatty acids may attenuate some of the gut injury and inflammation‐associated ulcerative colitic (UC). The objectives of this study were to (a) assess the antiinflammatory activity of sulfasalazine (SAZ), a drug known to be effective in the treatment of human UC in a model of chronic granulomatous colitis in rats and (b) determine whether enteral diets supplemented with either FO or two indigestible oligosaccharides (fructooligosaccharide, FOS;xylooligosaccharide, XOS) could attenuate the inflammation observed in a model of chronic granulomatous colitis. In one series of experiments, female Lewis rats were randomized into three groups consisting of a sham‐operated control group, a colitic group, and a colitic group in which rats were given oral sulfasalazine (SAZ) immediately after induction of colitis and continued for 3 weeks. Chronic granulomatous colitis with liver and spleen inflammation was induced by subserosal (intramural) injection of purified peptidoglycan‐polysaccharide (PG/PS) into the distal colon. Sham‐operated rats were injected with human serum albumin. All rats received standard lab chow. In a second series of experiments, female Lewis rats were randomized into six groups consisting of four colitic groups fed enteral diets, a colitic group fed chow, and a sham‐operated group fed a control enteral diet. Enteral diets (300 kcal/kg/day) contained either FO, FOS/gum arabic, XOS/gum arabic, or no bioactive ingredient (control diet). All rats were fed for 1 week before induction of colitis. Rats consumed the diets for 3 additional weeks before being killed. SAZ significantly attenuated the PG/PS‐induced increases in myeloperoxidase (MPO) activity as well as significantly reduced the PG/PS‐induced increases in liver and spleen weights. Control (enteral diet) as well as the FO and XOS diets significantly attenuated the increase in colon weight when compared with chow‐fed rats. We also found that the FO and XOS diets significantly attenuated the PG/PS‐induced increases in colonic MPO activity and colon weight. The FOS and XOS diets significantly attenuated the PG/PS‐induced increases in liver weights when compared with PG/PS + chow‐fed animals. The antiinflammatory activity of these diets was confirmed by means of histological inspection showing an inhibition of inflammation and maintenance of crypt cell integrity. These results demonstrate that a complete e