Epithelial Function and Development Group, Department of Veterinary Preclinical Sciences, University of Liverpool, Liverpool, UK.
Br J Nutr. 2010 Sep;104(5):637-46. doi: 10.1017/S0007114510000917. Epub 2010 Mar 26.
In an intensive livestock production, a shorter suckling period allows more piglets to be born. However, this practice leads to a number of disorders including nutrient malabsorption, resulting in diarrhoea, malnutrition and dehydration. A number of strategies have been proposed to overcome weaning problems. Artificial sweeteners, routinely included in piglets' diet, were thought to enhance feed palatability. However, it is shown in rodent models that when included in the diet, they enhance the expression of Na+/glucose co-transporter (SGLT1) and the capacity of the gut to absorb glucose. Here, we show that supplementation of piglets' feed with a combination of artificial sweeteners saccharin and neohesperidin dihydrochalcone enhances the expression of SGLT1 and intestinal glucose transport function. Artificial sweeteners are known to act on the intestinal sweet taste receptor T1R2/T1R3 and its partner G-protein, gustducin, to activate pathways leading to SGLT1 up-regulation. Here, we demonstrate that T1R2, T1R3 and gustducin are expressed together in the enteroendocrine cells of piglet intestine. Furthermore, gut hormones secreted by the endocrine cells in response to dietary carbohydrates, glucagon-like peptides (GLP)-1, GLP-2 and glucose-dependent insulinotrophic peptide (GIP), are co-expressed with type 1 G-protein-coupled receptors (T1R) and gustducin, indicating that L- and K-enteroendocrine cells express these taste elements. In a fewer endocrine cells, T1R are also co-expressed with serotonin. Lactisole, an inhibitor of human T1R3, had no inhibitory effect on sweetener-induced SGLT1 up-regulation in piglet intestine. A better understanding of the mechanism(s) involved in sweetener up-regulation of SGLT1 will allow the identification of nutritional targets with implications for the prevention of weaning-related malabsorption.
在集约化的畜牧业生产中,缩短哺乳时间可以让更多的仔猪出生。然而,这种做法会导致多种紊乱,包括营养吸收不良,导致腹泻、营养不良和脱水。人们提出了许多策略来克服断奶问题。人工甜味剂通常包含在仔猪的饮食中,被认为可以提高饲料的适口性。然而,在啮齿动物模型中表明,当包含在饮食中时,它们会增强钠/葡萄糖共转运蛋白(SGLT1)的表达和肠道吸收葡萄糖的能力。在这里,我们表明,在仔猪饲料中添加人工甜味剂糖精和新橙皮苷二氢查尔酮的组合可以增强 SGLT1 的表达和肠道葡萄糖转运功能。人工甜味剂已知作用于肠道甜味受体 T1R2/T1R3 及其伴侣 G 蛋白 gustducin,激活导致 SGLT1 上调的途径。在这里,我们证明 T1R2、T1R3 和 gustducin 一起在仔猪肠道的肠内分泌细胞中表达。此外,内分泌细胞响应膳食碳水化合物分泌的肠道激素,如胰高血糖素样肽 (GLP)-1、GLP-2 和葡萄糖依赖性胰岛素释放肽 (GIP),与 1 型 G 蛋白偶联受体 (T1R) 和 gustducin 共表达,表明 L-和 K-肠内分泌细胞表达这些味觉元素。在较少的内分泌细胞中,T1R 也与 5-羟色胺共表达。乳糖醇,一种人类 T1R3 的抑制剂,对甜味剂诱导的仔猪肠道 SGLT1 上调没有抑制作用。更好地了解甜味剂上调 SGLT1 涉及的机制将允许确定与预防断奶相关的吸收不良相关的营养靶标。