Platel Jean-Claude, Heintz Tristan, Young Stephanie, Gordon Valerie, Bordey Angélique
Department of Neurosurgery, Yale University School of Medicine, 333 Cedar Street, FMB 422, New Haven, CT 06520-8082, USA.
J Physiol. 2008 Aug 15;586(16):3783-93. doi: 10.1113/jphysiol.2008.155879. Epub 2008 Jun 19.
In the postnatal subventricular zone (SVZ), neuroblasts migrate in chains along the lateral ventricle towards the olfactory bulb. AMPA/kainate receptors as well as metabotropic glutamate receptors subtype 5 (mGluR5) are expressed in SVZ cells. However, the cells expressing these receptors and the function of these receptors remain unexplored. We thus examined whether SVZ neuroblasts express mGluR5 and Ca(2+)-permeable kainate receptors in mouse slices. Doublecortin (DCX)-immunopositive cells (i.e. neuroblasts) immunostained positive for mGluR5 and GLU(K5-7)-containing kainate receptors. RT-PCR from approximately 10 GFP-fluorescent cell aspirates obtained in acute slices from transgenic mice expressing green fluorescent protein (GFP) under the DCX promoter showed mGluR5 and GLU(K5) receptor mRNA in SVZ neuroblasts. Patch-clamp data suggest that approximately 60% of neuroblasts express functional GLU(K5)-containing receptors. Activation of mGluR5 and GLU(K5)-containing receptors induced Ca(2+) increases in 50% and 60% of SVZ neuroblasts, respectively, while most neuroblasts displayed GABA(A)-mediated Ca(2+) responses. To examine the effects of these receptors on the speed of neuroblast migration, we developed a whole-mount preparation of the entire lateral ventricle from postnatal day (P) 20-25 DCX-GFP mice. The GABA(A) receptor (GABA(A)R) antagonist bicuculline increased the speed of neuroblast migration by 27%, as previously reported in acute slices. While the mGluR5 antagonist MPEP did not affect the speed of neuroblast migration, the homomeric and heteromeric GLU(K5) receptor antagonists, NS3763 and UB302, respectively, increased the migration speed by 38%. These data show that although both GLU(K5) receptor and mGluR5 activations increase Ca(2+) in neuroblasts, only GLU(K5) receptors tonically reduce the speed of neuroblast migration along the lateral ventricle.
在出生后的脑室下区（SVZ），神经母细胞沿着侧脑室成链状向嗅球迁移。AMPA/海人酸受体以及代谢型谷氨酸受体5亚型（mGluR5）在SVZ细胞中表达。然而，表达这些受体的细胞以及这些受体的功能仍未得到探索。因此，我们在小鼠脑片中检测了SVZ神经母细胞是否表达mGluR5和Ca(2+)通透的海人酸受体。双皮质素（DCX）免疫阳性细胞（即神经母细胞）对mGluR5和含GLU(K5 - 7)的海人酸受体免疫染色呈阳性。从在DCX启动子控制下表达绿色荧光蛋白（GFP）的转基因小鼠急性脑片中获取的约10个GFP荧光细胞吸出物进行RT-PCR，结果显示SVZ神经母细胞中有mGluR5和GLU(K5)受体mRNA。膜片钳数据表明，约60%的神经母细胞表达功能性含GLU(K5)的受体。mGluR5和含GLU(K5)的受体激活分别在50%和60%的SVZ神经母细胞中诱导Ca(2+)增加，而大多数神经母细胞表现出GABA(A)介导的Ca(2+)反应。为了检测这些受体对神经母细胞迁移速度的影响，我们制备了出生后第20 - 25天DCX - GFP小鼠整个侧脑室的整装标本。如先前在急性脑片中所报道的，GABA(A)受体（GABA(A)R）拮抗剂荷包牡丹碱使神经母细胞迁移速度提高了27%。虽然mGluR5拮抗剂MPEP不影响神经母细胞迁移速度，但同聚体和异聚体GLU(K5)受体拮抗剂NS3763和UB302分别使迁移速度提高了38%。这些数据表明，尽管GLU(K5)受体和mGluR5激活均能使神经母细胞中的Ca(2+)增加，但只有GLU(K5)受体持续性地降低神经母细胞沿侧脑室迁移的速度。
