Shinohara H, Goda T, Takase S
Department of Education, Miyazaki University, Japan.
J Nutr Sci Vitaminol (Tokyo). 1992 Aug;38(4):365-74. doi: 10.3177/jnsv.38.365.
The effect of jejunum-bypass operation on lactase in rat small intestine was examined. Three groups of four or five rats were designated as jejunum-bypassed, sham-operated and normal rats. All animals including normal rats received by pair-feeding 5% glucose/1% NaCl for 5 days following the operation; thereafter they were fed ad libitum the laboratory chow diet. Three weeks after the jejunal bypass operation, the proximal ileum exhibited a hyperplasia as evidenced by a concomitant increase in mucosal contents of both total proteins and DNA. The specific activity of lactase in this segment was significantly lower in the operated rats than sham-operated controls, whereas the specific activity of sucrase in this segment was significantly elevated. The reduction of lactase activity was also evident in the proximal jejunal segment as well as in the distal jejunum which was deprived of luminal nutrition, suggesting that some hormonal factor(s) might be involved in the decrease of lactase activity in jejunum-bypassed animals. Electroimmunoassay revealed that the amount of immunoreactive lactase also declined in the operated rats relative to the sham-operated controls. Our results thus suggest that lactase activity in residual ileum is not only unable to compensate for the loss of digestive-absorptive surface of jejunum, but lactase activity even decreases following jejunum-bypass operation.
研究了空肠旁路手术对大鼠小肠乳糖酶的影响。将三组每组四或五只大鼠分别指定为空肠旁路组、假手术组和正常大鼠组。所有动物，包括正常大鼠，在手术后通过配对喂养给予5%葡萄糖/1%氯化钠，持续5天；此后，它们自由采食实验室常规饲料。空肠旁路手术后三周，近端回肠出现增生，表现为总蛋白和DNA的黏膜含量同时增加。该节段中乳糖酶的比活性在手术大鼠中显著低于假手术对照组，而该节段中蔗糖酶的比活性显著升高。乳糖酶活性的降低在近端空肠段以及缺乏腔内营养的远端空肠中也很明显，这表明某些激素因素可能参与了空肠旁路动物乳糖酶活性的降低。电免疫分析显示，与假手术对照组相比，手术大鼠中免疫反应性乳糖酶的量也有所下降。因此，我们的结果表明，残余回肠中的乳糖酶活性不仅无法补偿空肠消化吸收表面的损失，而且在空肠旁路手术后乳糖酶活性甚至会降低。
