Rings E H, Krasinski S D, van Beers E H, Moorman A F, Dekker J, Montgomery R K, Grand R J, Büller H A
Department of Pediatrics, University of Amsterdam, The Netherlands.
Gastroenterology. 1994 May;106(5):1223-32. doi: 10.1016/0016-5085(94)90013-2.
BACKGROUND/AIMS: Developmental changes of lactase activity along the proximal-to-distal axis of the small intestine are poorly understood. A study of delineate lactase gene expression at the cellular level was undertaken.
The topographical regulation of lactase was studied in conjunction with sucrase-isomaltase in proximal, middle, and distal segments of 0-, 7-, 14-, 16-, 18-, 21-, and 28-day-old and adult rats using in sity hybridization, immunohistochemistry, and ribonuclease protection assays.
From 0 to 16 days, lactase messenger RNA (mRNA) and protein were abundant along the total length of the small intestine. However, at weaning, lactase mRNA and protein were no longer detectable in the terminal ileum. After 28 days, zones of reduced lactase expression were found in the duodenum and terminal ileum. These zones demonstrated expression of lactase protein in scattered enterocytes along the villus (patchy expression). In contrast, sucrase-isomaltase was first detected at 16 days, with patchy expression along the total small intestine; at 21 days it was abundant.
Concordant changes in both lactase mRNA and protein detection during development suggest that the horizontal gradient of lactase enzyme expression is dependent on lactase mRNA abundance. Furthermore, zones of patchy lactase expression appear around weaning and flank the area of high lactase expression in the midintestine. Patchy expression is also found for sucrase-isomaltase before weaning.
背景/目的：人们对乳糖酶活性沿小肠近端至远端轴的发育变化了解甚少。因此开展了一项在细胞水平描绘乳糖酶基因表达的研究。
使用原位杂交、免疫组织化学和核糖核酸酶保护试验，结合蔗糖酶-异麦芽糖酶，对0日龄、7日龄、14日龄、16日龄、18日龄、21日龄、28日龄的大鼠及成年大鼠的近端、中段和远端小肠段的乳糖酶进行地形调节研究。
从0日龄到16日龄，乳糖酶信使核糖核酸（mRNA）和蛋白质在小肠全长中含量丰富。然而，在断奶时，回肠末端不再能检测到乳糖酶mRNA和蛋白质。28日龄后，在十二指肠和回肠末端发现乳糖酶表达降低的区域。这些区域显示乳糖酶蛋白在沿绒毛的散在肠细胞中表达（斑片状表达）。相比之下，蔗糖酶-异麦芽糖酶在16日龄时首次被检测到，在整个小肠中呈斑片状表达；在21日龄时含量丰富。
发育过程中乳糖酶mRNA和蛋白质检测的一致变化表明，乳糖酶表达的水平梯度取决于乳糖酶mRNA的丰度。此外，斑片状乳糖酶表达区域在断奶前后出现，位于小肠中部高乳糖酶表达区域的两侧。在断奶前蔗糖酶-异麦芽糖酶也有斑片状表达。
