Houghton Scott G, Zarroug Abdalla E, Duenes Judith A, Fernandez-Zapico Martin E, Sarr Michael G
Department of Surgery, GI Research Unit, Alfred 2, St. Mary's Hospital, Mayo Clinic College of Medicine, Rochester, MN 55905, USA.
Surgery. 2006 Apr;139(4):542-9. doi: 10.1016/j.surg.2005.09.002.
Protein and messenger RNA (mRNA) levels of the hexose transporters sodium-dependent glucose transporter-1, glucose transporter 2, and glucose transporter 5 follow a (daily) diurnal rhythm in rat jejunum. Because vagal innervation mediates the diurnal activity of other proteins in the rat small bowel, we hypothesized that the diurnal variation of mRNA and protein levels of these hexose transport proteins are mediated by vagal innervation.
Forty-eight rats kept in a strictly maintained, alternating 12-hour light-dark room underwent either sham laparotomy (n = 24) or bilateral total abdominal vagotomy (n = 24). Four weeks postoperatively, jejunal mucosa was harvested from 6 rats in each group at 3 am, 9 am, 3 pm and 9 pm; mRNA levels were determined by reverse transcription real-time polymerase chain reaction and protein levels by semiquantitative Western blot analysis. Transporter mRNA and protein levels were expressed as a ratio to the corresponding mRNA and protein levels of the stably expressed housekeeping gene glyceraldehyde-6-phosphate dehydrogenase.
mRNA and protein levels for all 3 hexose transporters showed diurnal variation in sham controls (P < or = .01 for all). After vagotomy, although mRNA levels of all 3 transporters showed diurnal variation (each P < .01), diurnal variation in all 3 hexose transporter protein levels was abolished (P > .10 for all).
Vagal innervation appears to differentially mediate the diurnal changes in hexose transporter mRNA and protein expression in the rat jejunum by posttranscriptional, and/or posttranslational processes.
己糖转运蛋白钠依赖性葡萄糖转运蛋白1、葡萄糖转运蛋白2和葡萄糖转运蛋白5的蛋白质及信使核糖核酸（mRNA）水平在大鼠空肠中呈现（每日的）昼夜节律。由于迷走神经支配介导了大鼠小肠中其他蛋白质的昼夜活性，我们推测这些己糖转运蛋白的mRNA和蛋白质水平的昼夜变化是由迷走神经支配介导的。
将48只饲养在严格维持的12小时明暗交替房间中的大鼠进行假剖腹手术（n = 24）或双侧全腹迷走神经切断术（n = 24）。术后四周，在凌晨3点、上午9点、下午3点和晚上9点从每组的6只大鼠中采集空肠黏膜；通过逆转录实时聚合酶链反应测定mRNA水平，通过半定量蛋白质印迹分析测定蛋白质水平。转运蛋白mRNA和蛋白质水平表示为与稳定表达的管家基因甘油醛-6-磷酸脱氢酶相应的mRNA和蛋白质水平的比值。
在假手术对照组中，所有3种己糖转运蛋白的mRNA和蛋白质水平均呈现昼夜变化（所有P≤0.01）。迷走神经切断术后，虽然所有3种转运蛋白的mRNA水平呈现昼夜变化（每种P<0.01），但所有3种己糖转运蛋白的蛋白质水平的昼夜变化均消失（所有P>0.10）。
迷走神经支配似乎通过转录后和/或翻译后过程，以不同方式介导大鼠空肠中己糖转运蛋白mRNA和蛋白质表达的昼夜变化。
