Objective To observe the effect of ginsenoside Rgl on transport ability of peptide transport carrier PepT1 for bipeptid compound and on protein and mRNA expression of PepT1 in Caco-2 cells. Methods Caco-2 monolayers were grown on permeable supports for 28 days. Then the cultured Caco-2 cells were treated with ginsenoside Rgl or cyclic adenosine monophosphate (cAMP) inhibitor (Rp-8-Br-cAMP). Peptide transport activity was studied by using glycyl-sarcosine. PepT1 protein expression was detected by Western blot method, and PepT1 mRNA (SLC15A1) expression level was analyzed by real-time fluorescent quantitative polymerase chain reaction (PCR). Results At time points of 15, 30, 60 and 120 min, the glycyl-sareosine amount conveyed by Caco-2 cells was higher in ginsenoside Rg1 group than that in the blank control group ( P ＜ 0. 05 or P ＜ 0. 01 ), and was lower in the combination group of ginsenoside Rg1 and Rp-8-Br-cAMP than that in ginsenoside Rg1 group ( P ＜ 0. 05 or P ＜ 0. 01 ). After treatment with ginsenoside Rg1, the protein expression of PepT1 was increased and SLC15A1 expression level was down-regulated (P ＜ 0. 05 ). Conclusion Ginsenoside Rgl can promote the transport of glycyl-sarcosine in normal Caco-2 cells, and the mechanism is probably related with the enhancement of cytoplasm PepT1 inserting cell membrane and with the regulation of intracellular cAMP.%[目的]观察人参皂苷Rg1对Caco-2细胞肽转运载体PepT1转运二肽化合物的能力及其蛋白、mRNA表达的影响.[方法]Caco-2细胞长满瓶底后继续培养28d,然后给予人参皂苷Rg1(终浓度为50mmol/L)处理,并设立空白对照组及cAMP抑制剂(Rp-8-Br-cAMP)对照组,采用放射性同位素示踪技术比较Caco-2细胞对二肽化合物Glycyl-Sarcosine的转运能力,采用Western blot法测定Caco-2细胞膜上PepT1蛋白的表达,荧光定量PCR法测定PepT1mRNA(SLC15A1)的表达水平.[结果]人参皂苷Rg1处理组Caco-2细胞15、30、60、120min时点Glycyl-Sarcosine吸收转运累计量均显著高于空白对照组对应时点的量(P＜0.05或P＜0.01),人参皂苷Rg1与Rp-8-Br-cAMP合用组15、30、60、120min时点均显著低于相应时点单用人参皂苷Rg1组(P＜0.05或P＜0.01),人参皂苷Rg1处理后Caco-2细胞膜PepT1蛋白表达显著增加(P＜0.05);荧光定量PCR结果显示:人参皂苷Rg1能显著下调SLC15A1表达(P＜0.05).[结论]人参皂苷Rg1具有促进正常培养Caco-2细胞转运二肽化合物Glycyl-Sarcosine的作用,该作用可能与其促进胞浆中PepT1蛋白嵌入胞膜中发挥转运二肽的功能有关,该过程调控与胞内第二信使cAMP有一定的关系.
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