Zinc transporters in the rat mammary gland respond to marginal zinc and vitamin A intakes during lactation
Zinc transporters in the rat mammary gland respond to marginal zinc and vitamin A intakes during lactation
复制标题
DOI：
10.1093/jn/132.11.3280
复制
发表时间：
2002-11-01
影响因子：
4.2
通讯作者：
Lönnerdal, B
中科院分区：
文献类型：
--
作者：
Kelleher, SL;Lönnerdal, B
锌和维生素A的边际摄入在哺乳期很常见，一种微量营养素的缺乏可导致另一种微量营养素的继发性缺乏。然而，牛奶锌（Zn）浓度的变化，饮食中的锌或维生素A的阻力表明乳腺锌运输的严格调节。虽然几种哺乳动物的蛋白质已被确定和涉及锌的运输，负责乳腺锌运输和饮食锌和维生素A的调节机制是未知的。在这项研究中，我们确定了乳腺锌转运蛋白，并确定了边缘锌和维生素A摄入量对其水平的影响。在整个哺乳期，大鼠喂食对照组[25 mg Zn/kg，4个维生素A当量（RE）/g]、低Zn（10 mg Zn/kg）、低维生素A（0.4 RE/g）或低Zn（10 mg Zn/kg）和维生素A（0.4 RE/g）饮食。在乳腺中鉴定了ZnT-1、ZnT-2和ZnT-4，并通过免疫染色定位于浆膜（ZnT-1）或细胞内（ZnT-2和ZnT-4）。与对照组相比，低锌或低维生素A饮食的大鼠具有较低的ZnT-1蛋白和较高的ZnT-4 mRNA表达和蛋白水平。日粮锌和维生素A对锌转运蛋白mRNA表达和蛋白质水平有显著的交互作用。虽然总乳腺锌没有受到影响，乳腺金属硫蛋白水平较低，低锌喂养的大鼠和高，低维生素A喂养的大鼠，这表明不同的机制调节锌转运蛋白水平。这些结果表明，牛奶锌水平的维持，通过协调调节乳腺锌转运蛋白和文件的影响，维生素A对锌稳态在哺乳期的分子水平。
Marginal intake of zinc and vitamin A is common during lactation and a deficiency of one micronutrient can result in a secondary deficiency of the other. However, the resistance of milk zinc (Zn) concentration to changes in dietary Zn or vitamin A indicates tight regulation of mammary gland Zn transport. Although several mammalian proteins have been identified and implicated in Zn transport, the mechanisms responsible for mammary gland Zn transport and their regulation by dietary Zn and vitamin A are unknown. In this study, we identified mammary gland Zn transporters and determined effects of marginal Zn and vitamin A intakes on their levels. Rats were fed a control [25 mg Zn/kg, 4 retinol equivalents (RE)/g], a low Zn (10 mg Zn/kg), a low vitamin A (0.4 RE/g), or a low Zn (10 mg Zn/kg) and vitamin A (0.4 RE/g) diet throughout lactation. ZnT-1, ZnT-2 and ZnT-4 were identified in the mammary gland and localized to the serosal membrane (ZnT-1) or intracellularly (ZnT-2 and ZnT-4) by immunostaining. Rats fed a low Zn or low vitamin A diet had lower ZnT-1 protein and higher ZnT-4 mRNA expression and protein levels compared with controls. There was a significant interaction between dietary Zn and vitamin A on zinc transporter mRNA expression and protein levels. Although total mammary gland Zn was not affected, mammary gland metallothionein levels were lower in rats fed low Zn and higher in rats fed low vitamin A, suggesting different mechanisms regulating zinc transporter levels. These results indicate that milk Zn level is maintained through coordinated regulation of mammary gland zinc transporters and documents an effect of vitamin A on zinc homeostasis at the molecular level during lactation.