Ulshen M H, Grand R J
J Clin Invest. 1979 Oct;64(4):1097-1102. doi: 10.1172/JCI109548.
To identify the site of stimulation of sucrase by a sucrose diet, changes in sucrase-specific activity of jejunal mucosa were studied after introduction of sucrose diet to carbohydrate-deprived rats. Results were correlated with simultaneous changes in villus gradients of sucrase-specific activity. Simultaneous with the introduction of sucrose diet, [(3)H]thymidine (100 muCi) was administered intravenously, and rates of cell migration measured during adaptation to the new diet. After a 72-h fast, rats fed sucrose diet for 6, 12, or 18 h showed no change in sucrase-specific activity in either whole mucosa or villus gradients. However, within 18-24 h after starting a sucrose diet, there was a marked rise in whole mucosal sucrase-specific activity above fasting values (99 +/- 14 vs. 38 +/- 4 muM glucose/min per g protein, P < 0.001) in association with the development of a region of increased activity at the lower villus (154 +/- 22 vs. 60 +/- 9 muM glucose/min per g protein, P < 0.02, but with no change in villus tip activity (56 +/- 5 vs. 46 +/- 8 muM glucose/min per g protein). Similar changes were seen in animals fed 24 h of sucrose diet after a 72-h carbohydratefree diet. Fasted animals fed sucrose diet for 36 h had increased sucrase-specific activity at the villus tip (144 +/- 11 muM glucose/min per g protein) as well as at the lower villus region, and this pattern persisted at 1 wk of sucrose diet. Maximal activity patterns for isomaltase and maltase paralleled those for sucrase, but the villus gradients for lactase were unaffected by sucrose diet. The region of maximal sucrase-specific activity always coincided with or followed the leading edge of radioactivity as determined by liquid scintillation counting. Therefore, sucrose-mediated changes in sucrase activity of the jejunal mucosa in the rat appear to be initiated at the level of the crypt epithelial cell and are expressed after a latent period of 18-24 h during which these cells mature and migrate toward the villus tip.
为确定蔗糖饮食对蔗糖酶的刺激位点，在给碳水化合物缺乏的大鼠引入蔗糖饮食后，研究了空肠黏膜蔗糖酶比活性的变化。结果与蔗糖酶比活性的绒毛梯度的同时变化相关。在引入蔗糖饮食的同时，静脉注射[(3)H]胸腺嘧啶核苷（100μCi），并在适应新饮食期间测量细胞迁移速率。禁食72小时后，喂食蔗糖饮食6、12或18小时的大鼠，全黏膜或绒毛梯度中的蔗糖酶比活性均无变化。然而，在开始蔗糖饮食后的18 - 24小时内，全黏膜蔗糖酶比活性显著高于禁食值（99±14对38±4μM葡萄糖/分钟每克蛋白质，P<0.001），同时绒毛下部出现活性增加区域（154±22对60±9μM葡萄糖/分钟每克蛋白质，P<0.02），但绒毛顶端活性无变化（56±5对46±8μM葡萄糖/分钟每克蛋白质）。在72小时无碳水化合物饮食后喂食24小时蔗糖饮食的动物中也观察到类似变化。禁食动物喂食蔗糖饮食36小时后，绒毛顶端（144±11μM葡萄糖/分钟每克蛋白质）以及绒毛下部区域的蔗糖酶比活性增加，这种模式在蔗糖饮食1周时持续存在。异麦芽糖酶和麦芽糖酶的最大活性模式与蔗糖酶相似，但乳糖酶的绒毛梯度不受蔗糖饮食影响。通过液体闪烁计数确定，蔗糖酶比活性最高的区域总是与放射性前沿重合或紧随其后。因此，大鼠空肠黏膜蔗糖酶活性的蔗糖介导变化似乎始于隐窝上皮细胞水平，并在18 - 24小时的潜伏期后表现出来，在此期间这些细胞成熟并向绒毛顶端迁移。
