ONTOGENY OF GABA(A) RECEPTOR SUBUNIT MESSENGER-RNAS IN RAT SPINAL-CORD AND DORSAL-ROOT GANGLIA
ONTOGENY OF GABA(A) RECEPTOR SUBUNIT MESSENGER-RNAS IN RAT SPINAL-CORD AND DORSAL-ROOT GANGLIA
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DOI：
10.1002/cne.903380303
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发表时间：
1993-12-15
影响因子：
2.5
通讯作者：
BARKER, JL
中科院分区：
文献类型：
--
作者：
MA, W;SAUNDERS, PA;BARKER, JL
关于GABA(A)受体亚基在哺乳动物脊髓中的发育及其基因表达的了解相对较少。采用原位杂交和逆转录聚合酶链反应（RT-PCR）技术，研究了编码13个GABA(A)受体亚基（alpha1-6、beta1-3、gamma1-3和delta）的mrna在胚胎、出生后和成年大鼠脊髓和背根神经节（DRG）细胞中的表达。两种技术都显示了原来在大鼠脑中发现的所有亚基mrna的存在，除了无法检测到的alpha6和仅通过RT-PCR检测到的弱的delta。通过原位杂交在心室区（VZ）和地幔区（MZ）内发现了两组解剖学上独特的亚基mrna。在胚胎第13天（E13），三个α 4、β 1和γ 1亚基mrna仅在神经上皮细胞中出现，并且在胚胎第17天之前在VZ中仍可检测到。在MZ中，beta3亚基mRNA首先在E12位点检测到，而alpha2、alpha3、alpha5、beta2、gamma2和gamma3转录本出现在E13位点。MZ亚基mrna的表达在胚胎晚期/出生后早期达到峰值之前，从运动神经元到背角神经元沿腹背侧序列迅速增加和扩增。在出生后的发育过程中，通过区域选择性缺失，mRNA表达下降，alpha4, alpha5, beta1, beta2， gamma1和gamma3亚基mRNA几乎无法检测到。相比之下，alpha2、alpha3、beta3和gamma2转录本在成年期以不同的解剖分布持续存在。RT-PCR分析揭示了PCR产物强度的独特发育模式，其中大部分与杂交mRNA信号密度的发育变化相吻合。然而，RT-PCR在成人中扩增了微量的alpha1、alpha4、alpha5、beta1、beta2、gamma1、gamma3和delta亚基mrna，这些mrna在胶片放射自显像中没有发现，但在少量颗粒阳性细胞的乳浸切片中可以检测到。DRG细胞在胚胎发育过程中表达alpha2、alpha3、alpha5、beta2、beta3和gamma2亚基mrna，但在成人中只检测到alpha2、beta3和gamma2亚基mrna。主要在VZ的alpha4beta1gamma1亚基mrna的短暂表达与神经发生期相关，而MZ中alpha2、alpha3、beta3和gamma2亚基mrna的发育变化与先前报道的GABA表达和突触形成和消除的变化相似。这些结果提示早期表达的GABA和GABA(a)受体在大鼠脊髓发育中的作用。(C) 1993 Wiley-Liss, Inc.*
Relatively little is known about the development of GABA(A) receptor subunits and their gene expression in mammalian spinal cord. The expressions of mRNAs encoding 13 GABA(A) receptor subunits (alpha1-6, beta1-3, gamma1-3, and delta) in embryonic, postnatal, and adult rat spinal cord and dorsal root ganglia (DRG) cells were studied by in situ hybridization and reverse transcription-polymerase chain reaction (RT-PCR) analysis. Both techniques revealed the presence of all subunit mRNAs originally found in the rat brain, except for alpha6, which was not detectable, and delta, which was weakly detected only by RT-PCR. Two anatomically distinctive sets of subunit mRNAs were found by in situ hybridization within the ventricular zone (VZ) and mantle zone (MZ). The trio of alpha4, beta1, and gamma1 subunit mRNAs emerged exclusively in neuroepithelial cells at embryonic day 13 (E13) and remained detectable in the VZ until E17. In the MZ, beta3 subunit mRNA was first detected at E12, while alpha2, alpha3, alpha5, beta2, gamma2, and gamma3 transcripts appeared at E13. Expressions of the subunit mRNAs in the MZ rapidly increased and expanded in a ventrodorsal sequence from motoneurons to dorsal horn neurons before reaching a peak in the late embryonic/early postnatal period. The mRNA expressions declined during postnatal development, by region-selective depletion, with alpha4, alpha5, beta1, beta2, gamma1, and gamma3 subunit mRNAs becoming barely detectable. In contrast, alpha2, alpha3, beta3, and gamma2 transcripts persisted into adulthood with distinct anatomical distributions. RT-PCR analysis revealed unique developmental patterns in the intensities of PCR products, most of which were in good agreement with developmental changes in the densities of hybridized mRNA signals. However, RT-PCR amplified minute amounts of mRNAs for alpha1, alpha4, alpha5, beta1, beta2, gamma1, gamma3, and delta subunits in adults, which were not found in film autoradiograms, but could be detected in a few grain-positive cells in emulsion-dipped sections. DRG cells expressed alpha2, alpha3, alpha5, beta2, beta3, and gamma2 subunit mRNAs during embryogenesis but only alpha2, beta3, and gamma2 subunit mRNAs were reliably detected in the adult. The transient expression of alpha4beta1gamma1 subunit mRNAs primarily in the VZ correlates with the period of neurogenesis, while the developmental changes of alpha2, alpha3, beta3, and gamma2 subunit mRNAs in the MZ parallels previously reported changes in GABA expression and in synapse formation and elimination. These results implicate a role of early-expressed GABA and GABA(A) receptors in the development of rat spinal cord. (C) 1993 Wiley-Liss, Inc.*