In vivo regulation of intestinal absorption of amino acids by leptin

Abstract

Leptin is secreted by the gastric mucosa and is able to reach the intestinal lumen and bind to its receptors located in the apical membranes of enterocytes. We have previously demonstrated that apical leptin inhibits uptake of amino acids in rat intestine in vitro and in Caco-2 cells. The aim of the present work was to investigate the effect of leptin on absorption of amino acids using in vivo techniques, which generate situations closer to physiological conditions. In vivo intestinal absorption of amino acids in rats was measured by isolating a jejunal loop and using the single-pass perfusion system. Disappearance of glutamine (Gln), proline (Pro), and b-alanine (b-Ala) from the perfusate, in the absence or presence of leptin, was measured using a radioactivity method. Luminal leptin (25 nM) inhibited the absorption of 2 mM Pro, 5 mM b-Ala, and 5 mM Gln by approximately 45% after 5-15 min; the effect remained constant until the end of the experiment (80 min) and was rapidly and completely reversed when leptin was removed from the perfusion medium. Moreover, leptin was able to regulate the absorption of galactose and Gln in the same animal, indicating a direct action of the hormone on the specific transporters implicated in the uptake of each nutrient. The results of the present work indicate that luminal leptin decreases absorption of amino acids in vivo in a short-term manner and in a reversible way. These results, together with our previous findings, make it evident that leptin can be considered as a hormone which provides the intestine with a control mechanism to handle absorption of nutrients. Key Words" amino acids transporters " in vivo " leptin " rat intestine

Cloning, tissue distribution and effects of fasting on mRNA expression levels of leptin and ghrelin in red-bellied piranha (Pygocentrus nattereri)

“…This is consistent with what has been shown in mammals. In rats, leptin decreases intestinal absorption of amino acids (Fanjul et al, 2015) and sugars (Iñigo et al, 2007) and mice deficient for leptin receptors in intestinal epithelial cells have longer intestinal villi and are less susceptible to high fat diet-induced obesity (Tavernier et al, 2014). Leptin also seems to regulate gastrointestinal processes in fish, as in yellow catfish, the hepatic expression of the digestive enzyme hormone-sensitive lipase (HSL) is regulated by leptin .…”

Improved capacity to evaluate changes in intestinal mucosal surface area using mathematical modeling

“…Morphometric parameters are commonly used to quantify changes to intestinal mucosa in studies of intestinal mucosal growth and adaptation (Austin et al, ; Choi et al, ; Sueyoshi et al, ; Sun et al, ). Furthermore, quantification of MSA is important in studies of intestinal absorption and function (Fanjul, Barrenetxe, De Pablo‐Maiso, & Lostao, ; Snipes, ). Determination of changes to MSA generally relies upon two‐dimensional morphometric parameters as these are easy to obtain and are thought to offer an acceptable means of estimation.…”

The Relationship between Plasma Levels of Large Neutral Amino Acids and Leptin in Women with or Without Obesity

“…However, LNAA and leptin were significantly elevated in our obese women. Interestingly, a recent report showed leptin inhibits intestinal absorption of amino acids [17]. Further investigation on identifying the real action of leptin (systematic or local) on amino acids uptake in intestinal or adipose tissues is warranted.…”