Low-grade inflammation persists in many patients with clinically quiescentinflammatory bowel disease (IBD). The current study aimed to establish low-grade IBD model mice. In addition, the anti-inflammatory effect of the cholinesterase inhibitor neostigmine was alsoinvestigated in this model. C57BL/6J mice were used. Colitis was inducedby the addition of 0.1–3%(w/v) dextran sulfate sodium (DSS) todrinking water for 7 days. Following 3% DSS treatment, weight loss,appearance of bloody stool and changes in stool quality were evident byday 4 and peaked at day 7. DSS at 1% elicited low-grade inflammation inthe colonic mucosa and increased myeloperoxidase (MPO) activity. Inimmunohistochemical study, increased MPO-immunopositive neutrophils wereobserved in the colonic mucosa of low-grade colitis model. Neostigmine dose-dependently inhibited the increase of MPO activity. The α7-nicotinic receptor antagonist partly reversed anti-inflammatory effectof neostigmine. In conclusion, we suggest that low-gradeIBD model mice are established by using 1% DSS-containing drinking water, and neostigmine provides anti-inflammatory effect through the stimulation of α7-nicotinic receptors in this model.

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