Localization of metabotropic GABA receptor subunits GABAB1 and GABAB2 relative to synaptic sites in the rat developing cerebellum
Localization of metabotropic GABA receptor subunits GABAB1 and GABAB2 relative to synaptic sites in the rat developing cerebellum
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DOI：
10.1111/j.1460-9568.2006.04669.x
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发表时间：
2006-03-01
影响因子：
3.4
通讯作者：
Shigemoto, R
中科院分区：
文献类型：
--
作者：
Luján, R;Shigemoto, R
据报道，GABA(B1)和GABA(B2)这两个代谢型GABA亚基的密度最高，发生在浦肯野细胞棘和平行纤维曲张之间的谷氨酸能突触周围。为了确定这种分布是如何在发育过程中实现的，我们研究了出生后大鼠小脑中GABA(B1)和GABA(B2)亚单位的表达模式以及细胞和亚细胞定位。在光镜水平上，GABA(B1)和GABA(B2)亚单位在发育中的分子层中的免疫反应非常明显，特别是在浦肯野细胞。利用双重免疫荧光技术，我们证明了GABA(B1)在胶质细胞中瞬时表达。在电子显微镜水平上，GABA(B)受体的免疫反应总是在突触前和突触后被检测到。在突触前，GABA(B1)和GABA(B2)在各年龄段的平行纤维突触外膜中均有分布，GABA能轴突中的GABA(B1)和GABA(B2)很少。在突触后，GABA(B)受体定位于浦肯野细胞树突和棘突的突触外和突触周围质膜。定量分析和三维重建进一步揭示了浦肯野细胞表面的GABA(B1)亚单位从树突干到其最终目的地树突棘的渐进性发育运动。综上所述，这些结果表明，GABA(B)受体在小脑发育过程中经历了动态调节，与浦肯野细胞谷氨酸能突触的建立和成熟有关。
The highest densities of the two metabotropic GABA subunits, GABA(B1) and GABA(B2), have been reported as occurring around the glutamatergic synapses between Purkinje cell spines and parallel fibre varicosities. In order to determine how this distribution is achieved during development, we investigated the expression pattern and the cellular and subcellular localization of the GABA(B1) and GABA(B2) subunits in the rat cerebellum during postnatal development. At the light microscopic level, immunoreactivity for the GABA(B1) and GABA(B2) subunits was very prominent in the developing molecular layer, especially in Purkinje cells. Using double immunofluorescence, we demonstrated that GABA(B1) was transiently expressed in glial cells. At the electron microscopic level, immunoreactivity for GABA(B) receptors was always detected both pre- and postsynaptically. Presynaptically, GABA(B1) and GABA(B2) were localized in the extrasynaptic membrane of parallel fibres at all ages, and only rarely in GABAergic axons. Postsynaptically, GABA(B) receptors were localized to the extrasynaptic and perisynaptic plasma membrane of Purkinje cell dendrites and spines throughout development. Quantitative analysis and three-dimensional reconstructions further revealed a progressive developmental movement of the GABA(B1) subunit on the surface of Purkinje cells from dendritic shafts to its final destination, the dendritic spines. Together, these results indicate that GABA(B) receptors undergo dynamic regulation during cerebellar development in association with the establishment and maturation of glutamatergic synapses to Purkinje cells.