Abstract：
Two subtypes of group I metabotropic glutamate receptors (mGluRs), mGluR1 and mGluR5, participate in the regulation of cell excitability and synaptic plasticity in the central nervous system. They couple to the Gq/11 protein and release Ca2+ from the intracellular stores. In the marginal zone of the neonatal hippocampus, Cajal-Retzius (CR) cells, which control radial migration of neurons, express the subtype mGluR1. The adenosine A1 receptor (A1R) is also G-protein coupled and is extensively expressed in the central nervous system. The interactions among G-protein-coupled receptors have been predicted previously, however, there is insufficient evidence of functional interactions between naturally occurring receptors. In this study, potentiation of the mGluR1-mediated response by A1R activation was demonstrated in hippocampal CR cells. Fluorescence imaging revealed that the application of A1R agonists intensified mGluR1-induced elevation of intracellular Ca2+ concentration ([Ca2+]i). Activation of A1R did not change [Ca2+]i. The potentiated responses were independent of extracellular Ca2+ and prevented by the Gi inhibitor. The potentiation of mGluR1-induced [Ca2+]i. elevation was also enhanced by mGluR2/3 activation. These results suggest that mGluR1 and A1R cooperatively influence postnatal hippocampal development by facilitating Ca2+ mobilization in CR cells.
摘要：
I组代谢型谷氨酸受体（mGluRs）的两种亚型，mGluR1和mGluR5参与调节中枢神经系统的细胞兴奋性和突触可塑性。它们与Gq/11蛋白偶联并从细胞内储存释放Ca2+。在新生儿海马的边缘区,Cajal-Retzius(CR)细胞,控制神经元的径向迁移，表达亚型mGluR1。腺苷A1受体（A1R）也是G蛋白偶联的，并在中枢神经系统中广泛表达。以前已经预测了G蛋白偶联受体之间的相互作用，然而,没有足够的证据表明天然存在的受体之间的功能相互作用。在这项研究中,在海马CR细胞中证明了通过A1R激活mGluR1介导的反应的增强。荧光成像显示，A1R激动剂的应用加剧了mGluR1诱导的细胞内Ca2浓度（[Ca2]i）升高。A1R的激活没有改变[Ca2+]i。增强的反应与细胞外Ca2无关，并被Gi抑制剂阻止。mGluR1诱导的[Ca2]i的增强作用。mGluR2/3激活也增强了升高。这些结果表明，mGluR1和A1R通过促进CR细胞中的Ca2动员来共同影响出生后海马发育。
