胰高血糖素样肽-2在人体内的体内和体外降解

In vivo and in vitro degradation of glucagon-like peptide-2 in humans.

作者信息

Hartmann B, Harr M B, Jeppesen P B, Wojdemann M, Deacon C F, Mortensen P B, Holst J J

机构信息

Department of Medical Physiology, The Panum Institute, University of Copenhagen, Denmark.

出版信息

J Clin Endocrinol Metab. 2000 Aug;85(8):2884-8. doi: 10.1210/jcem.85.8.6717.

DOI:10.1210/jcem.85.8.6717

PMID:10946898

Abstract

Glucagon-like peptide-2 (GLP-2), an intestinal product of glucagon gene expression which induces intestinal growth in mice, has been proposed as a treatment for intestinal insufficiency. GLP-2 is metabolized extensively by dipeptidyl peptidase IV (DPP-IV) in rats, but less is known about its fate in humans. Therefore, GLP-2 metabolism was investigated in healthy volunteers after 1) a 500-Cal mixed meal (n = 6), 2) iv infusion of synthetic human GLP-2 (0.8 pmol/kg x min; n = 8), 3) a sc bolus injection (400 microg; n = 9), and 4) in vitro incubation in plasma and blood (1,000 pmol/L; n = 4). GLP-2 concentrations were determined by N-terminal RIA measuring only intact GLP-2, side-viewing RIA measuring intact and degraded forms [e.g. GLP-2-(3-33) arising from DPP-IV degradation], and high performance liquid chromatography (HPLC). Meal ingestion elevated plasma GLP-2 (intact, 16 +/- 3 to 73 +/- 10 pmol/L at 90 min), and HPLC revealed two immunoreactive components: intact GLP-2 (57 +/- 2%) and GLP-2-(3-33). GLP-2 infusion increased plasma levels [intact, 9 +/- 4 to 131 +/- 11 pmol/L; total, 23 +/- 7 to 350 +/- 18 pmol/L; the differences represent GLP-2-(3-33)]. The elimination t(1/2) values were 7.2 +/- 2 min (intact GLP-2) and 27.4 +/- 5.4 min [GLP-2-(3-33)], and MCRs were 6.8 +/- 0.6 and 1.9 +/- 0.3 mL/kg x min, respectively. Subcutaneous injection increased intact GLP-2 to maximally 1,493 +/- 250 pmol/L at 45 min, whereas total GLP-2 increased to 2,793 +/- 477 pmol/L at 90 min. At 60 min, plasma contained 69 +/- 1% intact GLP-2. In vitro the t(1/2) values were 8.0 +/- 1.5 h (plasma) and 3.3 +/- 0.3 h (blood). GLP-2-(3-33) was the only degradation product identified by HPLC, and a DPP-IV inhibitor abolished the degradation of GLP-2 in vitro. We conclude that GLP-2 is extensively degraded to GLP-2-(3-33) in humans, presumably by DPP-IV. Nevertheless, 69% remains intact 1 h after GLP-2 injection, supporting the possibility of sc use in patients with intestinal insufficiency.

摘要

胰高血糖素样肽-2（GLP-2）是胰高血糖素基因表达的一种肠道产物，可诱导小鼠肠道生长，已被提议用于治疗肠道功能不全。在大鼠中，GLP-2被二肽基肽酶IV（DPP-IV）广泛代谢，但对其在人体内的代谢情况了解较少。因此，在健康志愿者中进行了以下研究：1）摄入500千卡混合餐（n = 6）；2）静脉输注合成人GLP-2（0.8 pmol/kg×min；n = 8）；3）皮下推注（400微克；n = 9）；4）在血浆和血液中进行体外孵育（1000 pmol/L；n = 4）。通过仅测量完整GLP-2的N端放射免疫分析（RIA）、测量完整和降解形式[例如由DPP-IV降解产生的GLP-2-(3-33)]的侧视RIA以及高效液相色谱（HPLC）来测定GLP-2浓度。摄入餐后血浆GLP-2升高（完整形式，90分钟时从16±3 pmol/L升至73±10 pmol/L），HPLC显示出两种免疫反应性成分：完整GLP-2（57±2%）和GLP-2-(3-33)。输注GLP-2使血浆水平升高[完整形式，从9±4 pmol/L升至131±11 pmol/L；总量，从23±7 pmol/L升至350±18 pmol/L；差异代表GLP-2-(3-33)]。消除半衰期（t(1/2)）值分别为7.2±2分钟（完整GLP-2）和27.4±5.4分钟[GLP-2-(3-33)]，清除率（MCR）分别为6.8±0.6和1.9±0.3 mL/kg×min。皮下注射使完整GLP-2在45分钟时最大升至1493±250 pmol/L，而总GLP-2在90分钟时升至2793±477 pmol/L。在60分钟时，血浆中完整GLP-2占69±1%。在体外，t(1/2)值分别为8.0±1.5小时（血浆）和3.3±0.3小时（血液）。HPLC鉴定出GLP-2-(3-33)是唯一的降解产物，一种DPP-IV抑制剂可在体外消除GLP-2的降解。我们得出结论，在人体内GLP-2被广泛降解为GLP-2-(3-33)，推测是由DPP-IV介导。然而，GLP-2注射后1小时仍有69%保持完整，这支持了皮下注射用于肠道功能不全患者的可能性。