Summary

Background: Chronic nicotine administration has a dual effect on inflammatory bowel disease: augmentation of jejunitis and amelioration of colitis. We previously showed that chronic nicotine administration has divergent regional effects on small bowel and colonic mucosal mediators and blood flow.

Objective: To examine the effects of nicotine administration on cytokine levels in normal rat small bowel mucosa, colonic mucosa, and blood.

Methods: Male Sprague-Dawley rats weighing 200–250 g were given nicotine (12.5 μg/ml) that was dissolved in tap water. Rats were sacrificed on days 1, 2, 7 and 14 after nicotine initiation; blood was withdrawn, and small bowel and colon were resected, washed and weighed. Mucosal scrapings were extracted in 2 ml Krebs-Hemselest buffer for determination of interleukins-2, 6 and 10 using the Biosource International Immunoassay Kit.

Results: Nicotine decreased IL-10[1] and increased IL-6 levels in small bowel mucosa (from 3.5 ±  0.5 to 0.4 ± 0.1 pg/ml and from 1.9±0.4 to 13.6±0.4 pg/ml respectively; P < 0.05). Nicotine decreased IL-2 levels in the colon (from 15.8±3.0 to 7.9±1.0 pg/ml; P < 0.05), having no effect on IL-10 or IL-6 levels. Rats treated with nicotine had lower IL-6 and IL-2 blood levels compared to control rats.

Conclusions: Nicotine has different regional effects on small bowel and colonic cytokine mucosal levels, which might explain some of its opposite effects on small bowel and colonic inflammation.