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lesions. We chose restraint stress to prepare IBS rat models because this stress method is simple and provides equivalent stress for each rat. In humans, IBS is diagnosed based on the clinical symptoms. Symptoms are very important to confirm IBS even in the animal models created in our experiment. In the present study, rats showed an increased fecal pellet output and diarrhea as clinical signs. Although we could not evaluate visceral hypersensitivity as no increased CRH release was observed, it was possible to create IBS 278Figure 6　A: Comparison of enterochromaffin cell (EC cell) expression between the proximal small intestine and the distal small intestine in the restraint group. B: Comparison of EC cell expression between the proximal small intestine and the distal small intestine in the control group.Figure 7　A: The number of Enterochromaffin cells (EC cells) in the distal small intestine was compared between the restraint and the control groups. B: The number of EC cells in the proximal small intestine was compared between the restraint and control groups.rat models. There are three types of IBS: diarrheal, constipated, and mixed. The present study is a rat model of IBS with diarrhea.Currently, most studies on IBS focus on visceral hypersensitivity and the brain-gut interaction. Therefore, it is important to understand gastroin-testinal motility during IBS treatment. There are some reports about colon motility in IBS15-17). However, Hardy et al.18) reported that when comparisons were made between diarrhea-type and constipation-type IBS, it was observed that