乳源β-酪啡肽7对大鼠葡萄糖吸收的影响及其作用机制

Effect of β-casomorphin-7 from milk on the absorption of glucose in vitro and its mechanism

目的:探讨乳源活性肽β-酪啡肽-7(β-Casomorphin-7,β-CM7)应用于食品时对葡萄糖吸收的影响及其作用机制.方法:选用健康成年SD大鼠,分为对照组(0mol/Lβ-CM7),L低剂量组、M中剂量组、H高剂量组(终浓度分别为7.5×10-7,7.5×10-6,7.5×10-5mol/L).利用翻转离体小肠囊模型进行实验:(1)葡萄糖氧化酶法测定翻转后小肠内液葡萄糖含量;(2)比色法测定小肠黏膜Na+-K+-ATP酶活力;(3)荧光定量PCR法分析小肠黏膜组织中钠葡萄糖共转运载体(SGLT-1)和葡萄糖协助扩散转运载体(GLUT-2) mRNA的表达.结果:在离体环境下β-CM7在7.5×10-7-7.5×10-5mol/L浓度下对葡萄糖的吸收均有一定的抑制作用(1.09mol/L,1.24mol/L,1.12mol/L vs 1.74mol/L,P=0.01,0.04,0.02),能够降低Na+-K+-ATP酶活力(85.73,112.06,109.68 vs 114.93,P=0.004,0.73,0.54);荧光定量PCR结果发现:与对照组相比,β-CM7能够显著降低SGLT-1及GLUT-2 mRNA水平(0.46,0.58,0.77 vs 1.11,P=0.20,0.05,0.02;0.50,0.66,0.85 vs 1.14,P=0.30,0.14,0.03).结论:β-CM7可以通过降低Na+-K+-ATP酶活力及下调SGLT-1、GLUT-2 mRNA水平,减少大鼠小肠对葡萄糖的吸收.

AIM： To detect the influence of major peptide β-casomorphin-7 （β-CM7） from milk on the absorption of glucose, and its mechanism in the diet and healthy food. METHODS： In this study healthy adult SD rats were divided into control group （0 mol/L β-CM7）, low-dose group （7.5×10^-7mol/L β-CM7）, middle-dose group （7.5×10^4mol/L β-CM7） and high-dose group （7.5×10^5 mol/L β-CM7）. Reverted sacs of adult rats in vitro were performed which were dipped into culture sample including β-CM7 and glucose and we designed a few tests： （1） the concentration of glucose in reverted sacs was detected using oxidase method of glucose; （2） the activity of Naβ-K＋-ATPase in small intestinal mucosa was observed with colorimetric method; （3） the mRNA expressions of sodium-glucose transporter （SGLT-1） and facilitative glucose transporter （GLUT-2） in small intestinal mucosa were analyzed using the Real-time PCR. RESULTS：Compared with control group, β-CM7 of 7.5×10^7-7.5×10^-5 mol/L significantly induced glucose concentration in vitro （1.09, 1.24, 1.12 vs 1.74, P = 0.01, 0.04, 0.02）; the activity of Na＋-K＋-ATPase was reduced （85.73, 112.06, 109.68 vs 114.93, P = 0.004, 0.73, 0.54）; the mRNA expressions of SGLT-1 and GLUT-2 were also significantly reduced （0.77, 0.58, 0.46 vs 1.11, P = 0.20, 0.05, 0.02; 0.50, 0.66, 0.85 vs 1.14, P = 0.30, 0.14, 0.03）, compared with control group. CONCLUSION： The present data demonstrated that β-CM7 was able to reduce the absorption of glucose through inhibiting activity of Na＋- K＋-ATPase and the mRNA expression level of SGLT-1, GLUT-2 in small intestine of rats.