Department of Cell Biology, University of Calabria, Arcavacata di Rende (CS), Italy.
Nutr Metab Cardiovasc Dis. 2012 Jun;22(6):486-94. doi: 10.1016/j.numecd.2010.07.014. Epub 2010 Dec 24.
The anorexigenic glucagon-like peptide (GLP)-2 is produced by intestinal L cells and released in response to food intake. It affects intestinal function involving G-protein-coupled receptors. To verify whether GLP-2 acts as a cardiac modulator in mammals, we analysed, in the rat heart, the expression of GLP-2 receptors and the myocardial and coronary responses to GLP-2.
GLP-2 receptors were detected on ventricular extracts by quantitative real-time polymerase chain reaction (Q-RT-PCR) and Western blotting. Cardiac GLP-2 effects were analysed on Langendorff perfused hearts. Intracellular GLP-2 signalling was investigated on Langendorff perfused hearts and by Western blotting and enzyme-linked immunosorbent assay (ELISA) on ventricular extracts. By immunoblotting and Q-RT-PCR, we revealed the expression of ventricular GLP-2 receptors. Perfusion analyses showed that GLP-2 induces positive inotropism at low concentration (10-12 mol l(-1)), and negative inotropism and lusitropism from 10 to 10 mol l(-1). It dose-dependently constricts coronaries. The negative effects of GLP-2 were independent from GLP-1 receptors, being unaffected by exendin-3 (9-39) amide. GLP-2-dependent negative action involves Gi/o proteins, associates with a reduction of intracellular cyclic adenosine monophosphate (cAMP), an increase in extracellular signal regulated kinases 1 and 2 (ERK1/2) and a decrease in phospholamban phosphorylation, but is independent from endothelial nitric oxide synthase (eNOS) and protein kinase G (PKG). Finally, GLP-2 competitively antagonised β-adrenergic stimulation.
For the first time, to our knowledge, we found that: (1) the rat heart expresses functional GLP-2 receptors; (2) GLP-2 acts on both myocardium and coronaries, negatively modulating both basal and β-adrenergic stimulated cardiac performance; and (3) GLP-2 effects are mediated by G-proteins and involve ERK1/2.
肠 L 细胞产生的厌食性胰高血糖素样肽 (GLP)-2 会响应食物摄入而释放，它通过 G 蛋白偶联受体影响肠道功能。为了验证 GLP-2 是否在哺乳动物中充当心脏调节剂，我们在大鼠心脏中分析了 GLP-2 受体的表达以及 GLP-2 对心肌和冠状动脉的反应。
通过实时定量聚合酶链反应 (Q-RT-PCR) 和 Western blot 检测心室提取物中的 GLP-2 受体。在 Langendorff 灌流心脏上分析心脏 GLP-2 作用。通过 Langendorff 灌流心脏和 Western blot 以及心室提取物的酶联免疫吸附试验 (ELISA) 研究细胞内 GLP-2 信号转导。通过免疫印迹和 Q-RT-PCR 揭示了心室 GLP-2 受体的表达。灌流分析表明，GLP-2 在低浓度（10-12 mol l(-1)）时诱导正性变力作用，在 10 到 10 mol l(-1) 时诱导负性变力和正性松弛作用。它剂量依赖性地收缩冠状动脉。GLP-2 的负作用不依赖于 GLP-1 受体，不受 exendin-3 (9-39) 酰胺的影响。GLP-2 依赖性的负作用涉及 Gi/o 蛋白，与细胞内环磷酸腺苷 (cAMP) 减少、细胞外信号调节激酶 1 和 2 (ERK1/2) 增加和磷蛋白磷酸化减少相关，但与内皮型一氧化氮合酶 (eNOS) 和蛋白激酶 G (PKG) 无关。最后，GLP-2 竞争性拮抗β-肾上腺素刺激。
据我们所知，这是首次发现：(1) 大鼠心脏表达功能性 GLP-2 受体；(2) GLP-2 作用于心肌和冠状动脉，负性调节基础和β-肾上腺素刺激的心脏功能；(3) GLP-2 作用由 G 蛋白介导，并涉及 ERK1/2。
