Dept. of Food Science, Cornell Univ., Ithaca, NY 14853, USA.
J Food Sci. 2012 May;77(5):H96-H104. doi: 10.1111/j.1750-3841.2012.02658.x. Epub 2012 Apr 12.
We tested the hypothesis that rats adapt to the iron absorption inhibitory effects of tea by modifying the expression of salivary proteins. Thirty-six weanling rats were allocated into 6 groups. Two control groups were fed a semipurified diet containing 20 mg Fe(2+)/kg diet. Two groups were fed spray dried green tea infusion mixed into the diet (28.6 g tea/kg diet) and 2 groups were fed the control diet with a twice daily gavage of a tea solution (0.25 g tea/mL). Saliva samples were collected in 3 groups (control, gavage, and oral) on day 8 (acute) and in the remaining groups on day 31 (chronic). Iron absorption was assessed using a (58)Fe(3+) tracer administered on day 1 (acute) and day 24 (chronic). 2D gel electrophoresis and mass spectrometry were used to assess the composition of the saliva proteome. There was no significant difference in iron absorption between the 3 groups on either day 1 or day 24. Salivary proline-rich proteins and submandibular gland secretory protein increased to a greater extent in the oral group than in the gavage group, when compared to control, within the same exposure time period. Amylase, chitinase, deoxyribonuclease, cysteine-rich secretory protein 1, and parotid secretory protein all decreased to a greater extent in the oral tea group, compared to the control, within the same exposure time period. Our results show that green tea did not decrease iron absorption in rats but it did have a marked effect on the saliva proteome when given orally.
我们检验了一个假设，即大鼠通过改变唾液蛋白的表达来适应茶对铁吸收的抑制作用。将 36 只断奶大鼠分为 6 组。两组对照组喂食含有 20mgFe(2+)/kg 饮食的半纯化饮食。两组大鼠喂食喷雾干燥的绿茶浸提液（28.6g 茶/kg 饮食），两组大鼠喂食对照饮食，并每日两次用茶水（0.25g 茶/mL）灌胃。在第 8 天（急性）和第 31 天（慢性）收集 3 组（对照、灌胃和口服）的唾液样本。第 1 天（急性）和第 24 天（慢性）用（58）Fe(3+)示踪剂评估铁吸收。使用 2D 凝胶电泳和质谱分析评估唾液蛋白质组的组成。在第 1 天和第 24 天，三组大鼠的铁吸收没有明显差异。与灌胃组相比，在相同的暴露时间内，口服组的唾液脯氨酸丰富蛋白和颌下腺分泌蛋白的增加程度大于灌胃组。与对照组相比，在相同的暴露时间内，淀粉酶、几丁质酶、脱氧核糖核酸酶、富含半胱氨酸的分泌蛋白 1 和腮腺分泌蛋白在口服茶组中下降得更为明显。我们的结果表明，绿茶并没有降低大鼠的铁吸收，但当口服时，它确实对唾液蛋白质组有显著影响。
