缺氧复氧损伤后小肠上皮细胞刷状缘二肽转运载体生物学功能的改变及生长激素的调控作用

目的　探讨缺氧复氧损伤后小肠上皮细胞模型Caco 2细胞刷状缘二肽转运载体 (PepT1)生物学功能的变化及重组人生长激素(rhGH)对PepT1的调控作用。方法　建立Caco 2细胞单层培养模型和缺氧复氧损伤模型 ,比较常规培养的Caco 2细胞单层及缺氧复氧损伤后Caco 2细胞模型对底物头孢氨苄转运和摄取功能的变化 ;用rhGH对两种细胞模型进行干预 ,比较两者对底物的转运和摄取能力改变 ;同时分别比较各种情况下PepT1mRNA的变化。结果　缺氧复氧损伤后Caco 2细胞PepT1mRNA水平明显下降 ,对底物的摄取能力明显低于对照组 (P <0 0 5 ) ;正常培养的Caco 2细胞经rhGH孵育后对底物的转运和摄取能力明显强于对照组 (P <0 0 5 ) ;缺氧复氧损伤后的Caco 2细胞用rhGH孵育后对底物的转运和摄取能力明显提高 ,与单纯损伤组比较差异有统计学意义 (P <0 0 5 )。结论　缺氧复氧损伤后PepT1mRNA下降 ,在基因水平下调了肠上皮细胞刷状缘PepT1对二肽的转运和摄取能力 ;rhGH对正常培养的Caco 2细胞和缺氧复氧损伤的Caco 2细胞的二肽载体转运和摄取功能均有上调作用 ;rhGH是在基因水平调节PepT1的生物学功能

CHANGES IN BIOLOGICAL FUNCTION OF DIPEPTIDE TRANSPORTER IN Caco-2 CELLS TREATED WITH NORMAL AND HYPOXIA/REOXYGENATION AND REGULATORY EFFECTS OF GROWTH HORMONE

Objective To determine the regulatory effects of recombinant human growth hormone (rhGH) on dipeptide transporter (PepT1) in Caco 2 cells in normal culture and hypoxia/reoxygenation injury. Methods A human intestinal cell monolayer (Caco 2) was used as the in vitro model of human small intestine and cephalexin as the substrate for dipeptide transporter (PepT1). Caco 2 cells grown on Transwell membrane filters were preincubated for 120min with rhGH, the transport experiments of Cephalexin across apical membranes were conducted. Caco 2 cells grown on multiple well dishes (24 pores) were normally cultured or under hypoxia/reoxygenation condition, or preincubated for 120min with rhGH, and their uptake of cephalexin was then measured. Results The transport and uptake of cephelaxin across apical membranes of Caco 2 cells after preincubation with rhGH were significantly increased compared with controls ( P <0 05). Also, the addition of rhGH at a physiological concentrations (34nmol/L) to incubation medium greatly stimulated cephalexin uptake by hypoxia/reoxygenation injured Caco 2 cells ( P <0 05), while the biological function of PepT1 in injured Caco 2 cells without rhGH was markedly down regulated. Northern blot analysis showed that the level of PepT1 mRNA of rhGH treated injured Caco 2 cells was greatly increased compared to controls. Conclusion rhGH could greatly upregulate the physiological function of dipeptide transporters of Caco 2 cells. The alteration in gene expression may be a mechanism underlying the regulation of PepT1 function.