Gibson P, Folino M, McIntyre A, Rosella O, Finch C, Young G
Department of Medicine, University of Melbourne, Royal Melbourne Hospital, Parkville, Victoria, Australia.
J Gastroenterol Hepatol. 1995 May-Jun;10(3):324-30. doi: 10.1111/j.1440-1746.1995.tb01101.x.
The amount and type of dietary fibre ingested influences colonic luminal characteristics, especially the concentration of carbohydrate fermentation products such as butyrate. This study aimed to assess whether diets supplemented with fibres of differing fermentability (delivering different amounts of butyrate to the colon) influence mucosal activities of urokinase and brush border hydrolases, and epithelial turnover. Groups of five rats were fed one of four diets containing low (2%), highly fermented (guar 10% or oat bran 10%) or slowly fermented fibre (wheat bran 10%) for 4 weeks. Activities of urokinase, alkaline phosphatase, dipeptidyl peptidase IV and maltase were measured in mucosal homogenates of proximal and distal colon and from rectum. Proliferative kinetics were assessed in distal and proximal colon by the metaphase arrest technique. Hydrolase activities were similar across all four dietary groups but a significant difference was found for urokinase (P = 0.014). This was due to a reduction in urokinase activities of > 30% at the three sites in the wheat bran group compared with the other groups. Of proliferative indices, only crypt column height differed across the groups (P = 0.038) and was highest in rats fed wheat bran and lowest in those fed the low fibre diet (P = 0.047). The proportion of mitoses in the top one-fifth of the crypt also differed across groups (P = 0.038) due to the high values in the distal colon of the low fibre group. Thus, addition of a slowly fermented (but not highly fermented) fibre to the diet of rats reduces net urokinase activity in large bowel mucosa and increases the life span of colonic epithelial cells without changing activities of brush border hydrolases.
摄入膳食纤维的量和类型会影响结肠腔内特征，尤其是碳水化合物发酵产物（如丁酸盐）的浓度。本研究旨在评估补充不同发酵性纤维（向结肠输送不同量的丁酸盐）的饮食是否会影响尿激酶和刷状缘水解酶的黏膜活性以及上皮细胞更新。将五组大鼠分别喂食四种饮食中的一种，这四种饮食分别含有低纤维（2%）、高发酵性纤维（瓜尔豆胶10%或燕麦麸10%）或低发酵性纤维（麦麸10%），持续4周。在近端结肠、远端结肠和直肠的黏膜匀浆中测量尿激酶、碱性磷酸酶、二肽基肽酶IV和麦芽糖酶的活性。通过中期阻断技术评估远端结肠和近端结肠的增殖动力学。所有四个饮食组的水解酶活性相似，但尿激酶活性存在显著差异（P = 0.014）。这是因为与其他组相比，麦麸组三个部位的尿激酶活性降低了30%以上。在增殖指数中，只有隐窝柱高度在各组间存在差异（P = 0.038），在喂食麦麸的大鼠中最高，在喂食低纤维饮食的大鼠中最低（P = 0.047）。由于低纤维组远端结肠的值较高，隐窝顶部五分之一处的有丝分裂比例在各组间也存在差异（P = 0.038）。因此，在大鼠饮食中添加低发酵性（而非高发酵性）纤维可降低大肠黏膜中的尿激酶净活性，增加结肠上皮细胞的寿命，同时不改变刷状缘水解酶的活性。
