Dopamine D2-like receptors are expressed in pancreatic beta cells and mediate inhibition of insulin secretion
Dopamine D2-like receptors are expressed in pancreatic beta cells and mediate inhibition of insulin secretion
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DOI：
10.1074/jbc.m505560200
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发表时间：
2005-11-04
影响因子：
4.8
通讯作者：
Maechler, P
中科院分区：
文献类型：
--
作者：
Rubí, B;Ljubicic, S;Maechler, P
多巴胺信号转导是由5个克隆的受体介导的，它们被分成D1样(D1和D5)和D2样(D2，D3和D4)家族。我们通过逆转录-聚合酶链式反应鉴定了这两个家族的多巴胺受体在INS-1E胰岛素分泌细胞以及啮齿动物和人的分离胰岛中的存在。免疫检测证实D2受体在INS-1E、原代啮齿动物细胞和人β细胞的胰岛素分泌颗粒上有表达。然后，我们测试了已识别的受体对β细胞功能的潜在影响。多巴胺(10mU M)和D2样受体激动剂奎比罗(5mM)抑制葡萄糖刺激的胰岛素分泌，在几个模型中进行了测试，即INS-1Eβ细胞、荧光激活细胞分选的原代大鼠β细胞以及大鼠、小鼠和人类来源的胰岛。胰岛素的胞吐受代谢和胞内钙变化的控制。葡萄糖诱导的线粒体超极化和ATP生成的测量表明，多巴胺和D2样激动剂不抑制葡萄糖代谢。另一方面，多巴胺减少了INS-1Eβ细胞由葡萄糖刺激引起的细胞膜去极化和胞浆钙升高。这些结果首次表明，多巴胺受体在胰岛β细胞中表达。多巴胺抑制葡萄糖刺激的胰岛素分泌，这种作用可以归因于D2样受体。关于多巴胺介导的抑制胰岛素释放的分子机制，我们的结果指向代谢-分泌耦合的远端步骤。因此，多巴胺在葡萄糖稳态中所起的作用可能涉及在胰岛β细胞中表达的多巴胺受体，调节胰岛素的释放。
Dopamine signaling is mediated by five cloned receptors, grouped into D1-like (D1 and D5) and D2-like (D2, D3 and D4) families. We identified by reverse transcription-PCR the presence of dopamine receptors from both families in INS-1E insulin-secreting cells as well as in rodent and human isolated islets. D2 receptor expression was confirmed by immunodetection revealing localization on insulin secretory granules of INS-1E and primary rodent and human beta cells. We then tested potential effects mediated by the identified receptors on beta cell function. Dopamine ( 10 mu M) and the D2-like receptor agonist quinpirole ( 5 mu M) inhibited glucose-stimulated insulin secretion tested in several models, i.e. INS-1E beta cells, fluorescence-activated cell-sorted primary rat beta cells, and pancreatic islets of rat, mouse, and human origin. Insulin exocytosis is controlled by metabolism coupled to cytosolic calcium changes. Measurements of glucose-induced mitochondrial hyperpolarization and ATP generation showed that dopamine and D2-like agonists did not inhibit glucose metabolism. On the other hand, dopamine decreased cell membrane depolarization as well as cytosolic calcium increases evoked by glucose stimulation in INS-1E beta cells. These results show for the first time that dopamine receptors are expressed in pancreatic beta cells. Dopamine inhibited glucose-stimulated insulin secretion, an effect that could be ascribed to D2-like receptors. Regarding the molecular mechanisms implicated in dopamine-mediated inhibition of insulin release, our results point to distal steps in metabolism-secretion coupling. Thus, the role played by dopamine in glucose homeostasis might involve dopamine receptors, expressed in pancreatic beta cells, modulating insulin release.