Nanthakumar N N, Henning S J
Department of Biology, University of Houston 77204.
Am J Physiol. 1993 Feb;264(2 Pt 1):G306-11. doi: 10.1152/ajpgi.1993.264.2.G306.
The goal of our study was to determine how sucrase-isomaltase (SI) gene expression in the rat small intestine is modulated by glucocorticoids during the second and third postnatal weeks. SI mRNA was quantitated by Northern blot and was compared with sucrase activities in the same tissue samples. The role of endogenous glucocorticoids was assessed by measuring SI mRNA and enzyme activity in rat pups adrenalectomized (ADX) on postnatal day 9. ADX pups showed a retarded appearance of sucrase activity compared with sham-operated control pups, and the appearance of SI mRNA paralleled the enzyme activity. To determine the role of exogenous glucocorticoids, a saturating dose of dexamethasone (Dex) was administered daily in three series of experiments starting on days 10, 16, and 18. In the day 10 series, Dex caused precocious appearance of both SI mRNA and sucrase activity. In the day 16 series, Dex accelerated the rate of rise of the two parameters, whereas by day 18 there was no significant effect of Dex. To investigate whether the accelerated rise in the day 16 series was associated with changes in epithelial cell kinetics, the location of SI protein was assessed by immunofluorescence staining. The results indicated that the effect of Dex at this age was due to faster emergence of SI-bearing enterocytes from the intestinal crypts.(ABSTRACT TRUNCATED AT 250 WORDS)
我们研究的目的是确定在出生后第二和第三周，糖皮质激素如何调节大鼠小肠中蔗糖酶-异麦芽糖酶（SI）基因的表达。通过Northern印迹法对SI mRNA进行定量，并与相同组织样本中的蔗糖酶活性进行比较。通过测量出生后第9天接受肾上腺切除术（ADX）的大鼠幼崽的SI mRNA和酶活性，评估内源性糖皮质激素的作用。与假手术对照幼崽相比，ADX幼崽的蔗糖酶活性出现延迟，并且SI mRNA的出现与酶活性平行。为了确定外源性糖皮质激素的作用，在三个系列实验中，从第10天、第16天和第18天开始每天给予饱和剂量的地塞米松（Dex）。在第10天的系列实验中，Dex导致SI mRNA和蔗糖酶活性过早出现。在第16天的系列实验中，Dex加速了这两个参数的上升速率，而到第18天，Dex没有显著影响。为了研究第16天系列实验中加速上升是否与上皮细胞动力学变化有关，通过免疫荧光染色评估SI蛋白的定位。结果表明，这个年龄段Dex的作用是由于携带SI的肠上皮细胞从肠隐窝中更快地出现。（摘要截短至250字）
