Epithelial response to high-grain diets involves alteration in nutrient transporters and Na+/K+-ATPase mRNA expression in rumen and colon of goats
Epithelial response to high-grain diets involves alteration in nutrient transporters and Na+/K+-ATPase mRNA expression in rumen and colon of goats
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DOI：
10.2527/jas.2012-5570
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发表时间：
2013-09-01
影响因子：
3.3
通讯作者：
Zebeli, Q.
中科院分区：
文献类型：
--
作者：
Metzler-Zebeli, B. U.;Hollmann, M.;Zebeli, Q.
mRNA 水平的新证据表明，给反刍动物饲喂高谷物饮食会导致瘤胃上皮分子反应的协调变化。然而，反刍动物的后肠上皮对增加膳食谷物水平的适应尚未建立。因此，本研究的目的是表征与瘤胃和结肠上皮中营养物运输和电化学梯度相关的 mRNA 表达的变化，以及饲喂不同谷物水平的生长山羊的瘤胃形态。山羊 (n = 6) 的饲料中添加 0%、30% 或 60% 大麦谷物，持续 6 周。最后一次喂食后2小时对山羊实施安乐死，并收集腹侧瘤胃和近端结肠的颅部的食糜和组织样本。与饲喂 0 和 30% 谷物日粮的山羊相比，饲喂 60% 谷物日粮的山羊表现出较低的瘤胃和结肠 pH 值（P < 0.01）和较高的结肠总 VFA 浓度（P < 0.05）。作为对瘤胃 pH 值降低的反应，饲喂 60% 谷物日粮的山羊比饲喂 0 % 和 30% 谷物日粮的山羊具有更大的角化（P < 0.05）和更厚的瘤胃上皮角质层。与0%和30%谷物日粮相比，60%谷物日粮使瘤胃上皮中MCT1表达上调（P < 0.05）45%，将MCT4和SGLT1表达下调（P < 0.05）28%和50%。因此，饲喂 60% 谷物日粮的山羊在结肠上皮中的 MCT1 和 ATP1A1 表达量高于饲喂 0 % 和 30% 谷物日粮的山羊（P < 0.05）。回归分析显示，瘤胃和结肠上皮中 MCT1 和 ATP1A1 的表达以及瘤胃角质层增厚与管腔 pH 值降低呈负相关（R-2 = 0.35 至 0.87，P < 0.05），表明较低 pH 下 mRNA 表达较高。相反，瘤胃上皮中的 MCT4 表达与管腔 pH 值呈正相关（R-2 = 0.95，P < 0.01）。总之，该模型研究的结果表明，具有最大颗粒水平的瘤胃和结肠分子上皮反应可能与抵消管腔酸化对上皮细胞细胞内稳态的影响有关，并同时增加 VFA 的全身吸收。
Emerging evidence at the mRNA level indicates that feeding high-grain diets to ruminants leads to coordinated changes in the molecular response of the rumen epithelium. Yet, epithelial adaptation of the hindgut to increasing dietary grain levels has not been established in ruminants. Therefore, the objective of this study was to characterize alterations in mRNA expression associated with nutrient transport and electrochemical gradients in rumen and colon epithelium, and rumen morphology in growing goats fed different grain levels. Goats (n = 6) were fed diets with increasing levels of 0, 30, or 60% barley grain for 6 wk. Goats were euthanized 2 h after their last feeding, and digesta and tissue samples of the cranial part of the ventral rumen and proximal colon were collected. Goats fed the 60% grain diet exhibited a lower ruminal and colonic pH (P < 0.01) and a greater colonic total VFA concentration (P < 0.05) compared with those fed the 0 and 30% grain diets. As response to the decreased ruminal pH, goats fed the 60% grain diet had a greater (P < 0.05) keratinization and thicker stratum corneum of the rumen epithelium than goats fed the 0 and 30% grain diets. The 60% grain diet upregulated (P < 0.05) MCT1 expression by 45% and downregulated (P < 0.05) the expression of MCT4 and SGLT1 by 28 and 50%, respectively, in rumen epithelium compared with the 0 and 30% grain diets. Accordingly, goats fed the 60% grain diet had a greater (P < 0.05) expression of MCT1 and ATP1A1 in colon epithelium than goats fed the 0 and 30% grain diets. Regression analyses showed negative relationships (R-2 = 0.35 to 0.87, P < 0.05) of MCT1 and ATP1A1 expression in rumen and colon epithelium and thickening of ruminal stratum corneum to decreasing luminal pH values, suggesting greater mRNA expression at lower pH. In contrast, MCT4 expression in rumen epithelium positively correlated to luminal pH (R-2 = 0.95, P < 0.01). In conclusion, results of this model study indicated that with the greatest grain level rumen and colon molecular epithelial responses may have been related to counteract the consequences of luminal acidification on intracellular homeostasis in epithelial cells and concomitantly to increase systemic absorption of VFA.