Shulman R J, Tivey D R, Sunitha I, Dudley M A, Henning S J
Children's Nutrition Research Center, Houston, TX 77030.
J Pediatr Gastroenterol Nutr. 1992 Feb;14(2):166-72. doi: 10.1097/00005176-199202000-00008.
Insulin, found in human and pig colostrum and mature milk, appears to influence small intestinal growth and development. Ileal lactase activity is increased when porcine insulin is added to feedings administered to newborn piglets. We studied 2-day-old miniature piglets to determine whether the increase in lactase activity is accompanied by changes in enterocyte expression of lactase activity, steady-state levels of lactase mRNA, and/or posttranscriptional changes in lactase processing. We randomized the piglets to receive bottle feedings of a swine-weaning milk formula with (group F + I) or without (group F) the addition of 85 mU/ml of regular porcine insulin. The piglets were fed for 6 days (to 8 days of age), after which they were killed and the small intestine removed for analysis. Despite large differences between groups in enterocyte expression of lactase activity in the ileum, no differences were noted in the level of ileal lactase mRNA. The relative proportions of the 207, 210, and 230 kDa precursors of the 160 kDa mature lactase protein were similar between groups. These data indicate that the insulin-induced increased expression of ileal lactase activity is not regulated at the level of its mRNA or at the level of processing of the polypeptide.
在人和猪的初乳及成熟乳中发现的胰岛素似乎会影响小肠的生长和发育。给新生仔猪喂食添加了猪胰岛素的饲料后，回肠乳糖酶活性会增加。我们研究了2日龄的小型仔猪，以确定乳糖酶活性的增加是否伴随着肠上皮细胞乳糖酶活性表达、乳糖酶mRNA稳态水平和/或乳糖酶加工过程中的转录后变化。我们将仔猪随机分为两组，一组（F + I组）接受添加了85 mU/ml常规猪胰岛素的猪断奶奶粉瓶饲，另一组（F组）接受未添加胰岛素的猪断奶奶粉瓶饲。仔猪喂食6天（至8日龄）后处死，取出小肠进行分析。尽管两组之间回肠肠上皮细胞乳糖酶活性表达存在很大差异，但回肠乳糖酶mRNA水平没有差异。两组之间160 kDa成熟乳糖酶蛋白的207 kDa、210 kDa和230 kDa前体的相对比例相似。这些数据表明，胰岛素诱导的回肠乳糖酶活性增加在其mRNA水平或多肽加工水平上不受调控。
