Jejelava Nino, Kaufman Sharon, Krieger Jean-Philippe, Terra Marcella Martins, Langhans Wolfgang, Arnold Myrtha
Physiology and Behavior Laboratory, Institute of Food, Nutrition, and Health, Swiss Federal Institute of Technology, ETH Zurich, Switzerland.
Federal University of Juiz de Fora-Minas Gerais , Juiz de Fora-Minas Gerais , Brazil.
Am J Physiol Regul Integr Comp Physiol. 2018 May 1;314(5):R724-R733. doi: 10.1152/ajpregu.00120.2017. Epub 2018 Jan 17.
Intestinal lymph supposedly provides a readout for the secretion of intestinal peptides. We here assessed how mesenteric lymph duct (MLD) lymph levels of glucagon-like peptide (GLP-1), insulin, and metabolites [glucose and triglycerides (TG)] evolve after isocaloric high- and low-fat diet (HFD and LFD) meals and how they compare with hepatic portal vein (HPV) plasma levels. Moreover, we examined the effects of intraperitoneally administered GLP-1 (1 or 10 nmol/kg) on these parameters. At 20 min after the HFD meal onset, GLP-1 levels were higher in MLD lymph than in HPV plasma. No such difference occurred with the LFD meal. Intraperitoneal injections of 10 nmol/kg GLP-1 before meals enhanced the meal-induced increases in MLD lymph and HPV plasma GLP-1 levels except for the MLD lymph levels after the HFD meal. Intraperitoneal injection of 1 nmol/kg GLP-1 only increased HPV plasma GLP-1 levels at 60 min after the HFD meal. GLP-1 injections did not increase the MLD lymph or HPV plasma GLP-1 concentrations beyond the physiological range, suggesting that intraperitoneal GLP-1 injections can recapitulate the short-term effects of endogenous GLP-1. Dipeptidyl peptidase IV (DPP-IV) activity in MLD lymph was lower than in HPV plasma, which presumably contributed to the higher levels of GLP-1 in lymph than in plasma. Insulin and glucose showed similar profiles in MLD lymph and HPV plasma, whereas TG levels were higher in lymph than in plasma. These results indicate that intestinal lymph provides a sensitive readout of intestinal peptide release and potential action, in particular when fat-rich diets are consumed.
肠淋巴液理应能反映肠肽的分泌情况。我们在此评估了等热量的高脂饮食（HFD）和低脂饮食（LFD）餐后，肠系膜淋巴管（MLD）淋巴液中胰高血糖素样肽（GLP-1）、胰岛素及代谢物[葡萄糖和甘油三酯（TG）]水平的变化情况，以及它们与肝门静脉（HPV）血浆水平的比较。此外，我们还研究了腹腔注射GLP-1（1或10 nmol/kg）对这些参数的影响。在HFD餐开始后20分钟，MLD淋巴液中的GLP-1水平高于HPV血浆中的水平。LFD餐时未出现这种差异。餐前腹腔注射10 nmol/kg GLP-1可增强餐食诱导的MLD淋巴液和HPV血浆GLP-1水平升高，但HFD餐后MLD淋巴液水平除外。腹腔注射1 nmol/kg GLP-1仅在HFD餐后60分钟增加了HPV血浆GLP-1水平。GLP-1注射并未使MLD淋巴液或HPV血浆GLP-1浓度升高超过生理范围，这表明腹腔注射GLP-1可重现内源性GLP-1的短期效应。MLD淋巴液中的二肽基肽酶IV（DPP-IV）活性低于HPV血浆中的活性，这可能是导致淋巴液中GLP-1水平高于血浆的原因。胰岛素和葡萄糖在MLD淋巴液和HPV血浆中的变化趋势相似，而淋巴液中的TG水平高于血浆。这些结果表明，肠淋巴液能灵敏地反映肠肽的释放及潜在作用，尤其是在摄入富含脂肪的饮食时。
