Fatima Javairiah, Iqbal Corey W, Houghton Scott G, Kasparek Michael S, Duenes Judith A, Zheng Ye, Sarr Michael G
Gastroenterology Research Unit (GU 1001), Department of Surgery, Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA.
J Gastrointest Surg. 2009 Apr;13(4):634-41. doi: 10.1007/s11605-008-0776-4. Epub 2008 Dec 11.
Expression and function of hexose transporters vary diurnally in rat small intestine; however, this subject remains unexplored in mice.
The aim of the study was to investigate the diurnal expression and function of hexose transporters SGLT1, GLUT2, and GLUT5 in mouse small bowel.
Twenty-four c57bl6 mice maintained in a 12-h light/dark room (6 AM: -6 PM: ) were sacrificed at 9 AM: , 3 PM: , 9 PM: , and 3 AM: (n = 6 each). In duodenal, jejunal, and ileal mucosa, total cellular mRNA and protein levels were quantitated by real-time PCR and semiquantitative Western blotting, respectively. The everted sleeve technique measured transporter-mediated glucose uptake at 9 AM: and 9 PM: .
mRNA expression of SGLT1, GLUT2, and GLUT5 varied diurnally in all three intestinal segments (p <or= 0.03). SGLT1, GLUT2, and GLUT5 protein levels varied diurnally in duodenum and jejunum (p < 0.05) but not in ileum. Transporter-mediated glucose uptake was greater at 9 PM: than 9 AM: (p <or= 0.04) in all three segments. V (max) was greater in duodenum (10 vs 6 nmol/cm/s) and jejunum (8 vs 5 nmol/cm/s) at 9 PM: compared to 9 AM: (p = 0.01); K (m) remained unchanged. mRNA levels of intestinal hexose transporters varied diurnally. Protein levels peaked 6-12 h later during dark cycle when >70% of food intake occurred; glucose transport followed a similar pattern with increased uptake at 9 PM: .
Hexose transporter expression and function vary diurnally with nocturnal feeding patterns of mice.
己糖转运蛋白的表达和功能在大鼠小肠中呈现昼夜变化；然而，这一课题在小鼠中尚未得到探索。
本研究旨在探讨己糖转运蛋白SGLT1、GLUT2和GLUT5在小鼠小肠中的昼夜表达及功能。
将24只饲养在12小时光照/黑暗环境（上午6点至下午6点）的C57BL6小鼠，分别于上午9点、下午3点、晚上9点和凌晨3点处死（每组n = 6只）。分别通过实时PCR和半定量蛋白质免疫印迹法对十二指肠、空肠和回肠黏膜中的总细胞mRNA和蛋白质水平进行定量分析。采用外翻肠囊技术测定上午9点和晚上9点时转运蛋白介导的葡萄糖摄取量。
SGLT1、GLUT2和GLUT5的mRNA表达在所有三个肠段均呈现昼夜变化（p≤0.03）。SGLT1、GLUT2和GLUT5的蛋白质水平在十二指肠和空肠中呈现昼夜变化（p < 0.05），但在回肠中无此变化。在所有三个肠段中，转运蛋白介导的葡萄糖摄取在晚上9点时均高于上午9点（p≤0.04）。与上午9点相比，晚上9点时十二指肠（10对6 nmol/cm/s）和空肠（8对5 nmol/cm/s）的V（max）更高（p = 0.01）；K（m）保持不变。肠道己糖转运蛋白的mRNA水平呈现昼夜变化。蛋白质水平在黑暗周期中进食量超过70%时的6 - 12小时后达到峰值；葡萄糖转运遵循类似模式，晚上9点时摄取量增加。
己糖转运蛋白的表达和功能随小鼠夜间进食模式呈现昼夜变化。
