Mitsui R, Karaki S-I, Kubo Y, Sugiura Y, Kuwahara A
Laboratory of Physiology, Graduate School of Nutritional and Environmental Sciences, Institute for Environmental Sciences, University of Shizuoka, Suruga-ku Shizuoka, Japan.
Neurogastroenterol Motil. 2006 Dec;18(12):1093-101. doi: 10.1111/j.1365-2982.2006.00847.x.
Dietary fibre consumption is known to be beneficial to increase stool bulk and frequency. In contrast, it is unclear whether chronic dietary fibre deficiency affects colonic motor functions, especially neuronally mediated muscle contractions. In this study, rats were fed a fibre-free diet or diet containing dietary fibre (cellulose or guar gum) for 27 days. Furthermore, neurogenic and myogenic contractions were evaluated in circular and longitudinal muscle strips of the distal colon. Additionally, the number of enterochromaffin (EC) cells, which play important roles in the initiation of the peristaltic reflex, was also examined by immunohistochemistry for serotonin. Myogenic contractions induced by carbachol or substance P were examined in the presence of tetrodotoxin. Circular muscle was hyposensitive to carbachol, but longitudinal muscle was hypersensitive to substance P in the fibre-free group. Nerve-mediated circular (5-20 Hz) and longitudinal (1-2 Hz) muscle contractions evoked by electrical field stimulation were attenuated in the fibre-free group and the latter response was almost abolished by atropine, suggesting functional changes of cholinergic neurons. EC cell number was decreased in the fibre-free group. In conclusion, changes in neurogenic and myogenic contractions and a decrease in EC cell number observed may affect colonic motility of the fibre-free group.
众所周知，食用膳食纤维有利于增加粪便量和排便频率。相比之下，目前尚不清楚慢性膳食纤维缺乏是否会影响结肠运动功能，尤其是神经介导的肌肉收缩。在本研究中，给大鼠喂食无纤维饮食或含膳食纤维（纤维素或瓜尔胶）的饮食27天。此外，还对远端结肠的环形和纵形肌条中的神经源性和肌源性收缩进行了评估。另外，还通过免疫组织化学检测血清素，检查了在蠕动反射起始中起重要作用的肠嗜铬（EC）细胞的数量。在存在河豚毒素的情况下，检测了由卡巴胆碱或P物质诱导的肌源性收缩。在无纤维组中，环形肌对卡巴胆碱反应迟钝，但纵形肌对P物质反应敏感。无纤维组中，电场刺激引起的神经介导的环形肌（5 - 20 Hz）和纵形肌（1 - 2 Hz）收缩减弱，且后者的反应几乎被阿托品消除，提示胆碱能神经元功能发生了变化。无纤维组中EC细胞数量减少。总之，观察到的神经源性和肌源性收缩的变化以及EC细胞数量的减少可能会影响无纤维组的结肠动力。
