- 愛知医科大学医学会雑誌 (ISSN:03010902)
- vol.35, no.2, pp.59-70, 2007-06
Background: Brain activation areas in relation to bowel stimuli have been reported using brain imaging techniques in patients with irritable bowel syndrome(IBS). However, the results are controversial. The aim of this study is to clarify responsible brain site(s) when stimulated by the rectal balloon distension-induced abdominal symptom in IBS in terms of braingut interactions. Methods: Seven healthy volunteers and five patients with diarrhea-predominant IBS based on the Rome II criteria were recruited. All were right-handed men. Rectal sensitivity was examined with balloon distension using a barostat device. Studies are performed with or without rectal distension(RD). Each task took 4 minutes. The subjects were assigned to have each twice task at the individual pain threshold level with 11 minute intervals. The changes in brain blood flow were evaluated using H_2 ^<15>O-water positron emission tomography. Subjects were asked rectal pain and stress level with visual analogue scale(VAS) before and soon after the respective task. Blood pressure, heart rate, and several serum stress-related substances were also investigated. Results: The threshold of pressure for rectal pain was significantly lower in the IBS patients(IBS=14.4mmHg, volunteers=26.3mmHg on average). The IBS patients showed a significant increase in blood flow in especially insula, and in thalamus at RD as compared with that in volunteers. Analyzing changes in VAS score before and after task, an increase of score about physical stress was significantly larger in the IBS patients in RD although no differences was noted in pain perceived score among all subjects in RD. A tendency of correlation was observed between the RD-induced increment in blood flow in insula and that in VAS score of stress-feeling. Conclusions: The IBS patients had a significantly lower pain threshold against RD. Under RD stress at an individual pain threshold, a significant objective activation in insula, subjective physical stress, and correlation between them were obtained, indicating the brain activation magnitude-correlated stress in IBS.