State Key Laboratory of Animal Nutrition, Department of Animal Nutrition and Feed Science, China Agricultural University, Beijing 100193, China.
Department of Pathology and Laboratory Medicine, Metabolic Diseases Institute, University of Cincinnati, Cincinnati, OH 45237, USA.
Nutrients. 2022 Apr 24;14(9):1777. doi: 10.3390/nu14091777.
Glutamine (Gln) is required for intestinal mucosal homeostasis, and it can promote triglyceride absorption. The intestinal mucosal mast cells (MMCs) are activated during fat absorption. This study investigated the potential role of Gln on fat absorption-induced activation of MMCs in rats. Lymph fistula rats (n = 24) were studied after an overnight recovery with the infusion of saline only, saline plus 85 mM L-glutamine (L-Gln) or 85 mM D-glutamine (D-Gln), respectively. On the test day, rats (n = 8/group) were given an intraduodenal bolus of 20% Intralipid contained either saline only (vehicle group), 85 mM L-Gln (L-Gln group), or 85 mM D-Gln (D-Gln group). Lymph was collected hourly for up to 6 h for analyses. The results showed that intestinal lymph from rats given L-Gln had increased levels of apolipoprotein B (ApoB) and A-I (ApoA-I), concomitant with an increased spectrum of smaller chylomicron particles. Unexpectedly, L-Gln also increased levels of rat mucosal mast cell protease II (RMCPII), as well as histamine and prostaglandin D (PGD) in response to dietary lipid. However, these effects were not observed in rats treated with 85 mM of the stereoisomer D-Gln. Our results showed that L-glutamine could specifically activate MMCs to degranulate and release MMC mediators to the lymph during fat absorption. This observation is potentially important clinically since L-glutamine is often used to promote gut health and repair leaky gut.
谷氨酰胺（Gln）是肠黏膜稳态所必需的，它可以促进甘油三酯吸收。肠黏膜肥大细胞（MMCs）在脂肪吸收过程中被激活。本研究旨在探讨 Gln 在脂肪吸收诱导的大鼠 MMC 激活中的潜在作用。在隔夜恢复后，通过分别输注生理盐水、生理盐水加 85mM L-谷氨酰胺（L-Gln）或 85mM D-谷氨酰胺（D-Gln），对淋巴管瘘大鼠（n=24）进行研究。在测试日，大鼠（n=8/组）接受十二指肠内 20% Intralipid 推注，分别含有生理盐水（载体组）、85mM L-Gln（L-Gln 组）或 85mM D-Gln（D-Gln 组）。每隔 1 小时收集淋巴，持续 6 小时进行分析。结果表明，给予 L-Gln 的大鼠肠淋巴中载脂蛋白 B（ApoB）和 A-I（ApoA-I）水平升高，同时出现更多的较小乳糜微粒。出乎意料的是，L-Gln 还增加了大鼠黏膜肥大细胞蛋白酶 II（RMCPII）以及组胺和前列腺素 D（PGD）的水平，以响应膳食脂质。然而，在给予 85mM 立体异构体 D-Gln 的大鼠中未观察到这些作用。我们的结果表明，L-谷氨酰胺可以特异性激活 MMC 以脱颗粒，并在脂肪吸收过程中将 MMC 介质释放到淋巴中。这一观察结果在临床上可能很重要，因为 L-谷氨酰胺常用于促进肠道健康和修复渗漏的肠道。
