Colocalization of metabotropic glutamate receptors in rat dorsal root ganglion cells
Colocalization of metabotropic glutamate receptors in rat dorsal root ganglion cells
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DOI：
10.1002/cne.21285
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发表时间：
2007-04-10
影响因子：
2.5
通讯作者：
Hargett, Gregory L.
中科院分区：
文献类型：
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作者：
Carlton, Susan M.;Hargett, Gregory L.
谷氨酸是中枢和外周神经系统中主要的兴奋性递质。代谢性谷氨酸受体（mGluRs）的发现表明，谷氨酸对神经元功能具有兴奋或抑制作用，I组mGluRs增强细胞兴奋性，而II和III组mGluRs降低兴奋性。本研究调查了mGluR亚型在大鼠L5背根神经节（DRG）细胞中的共定位，这些亚型分别代表I、II和III组。分析显示，III组表达量最高，75.0%的DRG细胞表达mGluR8，其次是II组，51.6%表达mGluR2/3，其次是I组，表达mGluR1 α的细胞仅为6.8%。mGluR8在小、中、大直径细胞中均有表达。而mGluR1 α和mGluR2/3主要在中小细胞中表达。大约一半表达I组mGluR1 α的细胞也表达II组mGluR2/3或III组mGluR8。这些mGluR1 α双标记的群体不太可能重叠，因为bb0.1.0%的mGluR1 α是三标记的。正如预期的那样，单标记的mGluR2/3和mGluR8细胞的比例很高，有相当数量的双标记细胞，每个群体中约有30%表达两种受体。由于DRG中表达mGluR1 α的细胞数量较少，因此三标记细胞的比例也较低（约为1-2%）。II和III组的流行表明谷氨酸可能对初级传入功能有实质性的抑制作用，在传递到脊髓之前减少和/或微调感觉输入。这些解剖学数据强调了谷氨酸可能在外周感觉传递中发挥的潜在抑制作用。
Glutamate is the main excitatory transmitter in both central and peripheral nervous systems. Discovery of metabotropic glutamate receptors (mGluRs) made it clear that glutamate can have excitatory or inhibitory effects on neuronal function, with group I mGluRs enhancing cell excitability but group II and III mGluRs decreasing excitability. The present study investigated the colocalization of mGluR subtypes representing groups I, II, or III in rat L5 dorsal root ganglion (DRG) cells. The analyses show that group III has the highest expression, with 75.0% of DRG cells expressing mGluR8, followed by group II, with 51.6% expressing mGluR2/3, followed by group I, with only 6.8% expressing mGluR1 alpha. mGluR8 is expressed by small, medium, and large diameter cells. In contrast, mGluR1 alpha and mGluR2/3 are expressed by mainly small and medium cells. Approximately half of cells expressing group I mGluR1 alpha also express either group II mGluR2/3 or group III mGluR8. These mGluR1 alpha double-labeled populations are not likely to overlap since > 1.0% of mGluR1 alpha are triple-labeled. As expected from the high percentage of single-labeled mGluR2/3 and mGluR8 cells, there is a considerable population of double-labeled cells with approximate to 30% of each population expressing both receptors. Due to the fact that the number of mGluR1 alpha-expressing cells in the DRG is low, the percentage of triple-labeled cells is also low (approximate to 1-2%). The prevalence of groups II and III indicate that glutamate could have a substantial inhibitory effect of primary afferent function, reducing and/or fine-tuning sensory input before transmission to the spinal cord. These anatomical data highlight the potential inhibitory role glutamate may play in peripheral sensory transmission.