Kawamoto M, Ohno K, Kuriyama K, Kubo T, Sato K
Department of Anatomy and Neuroscience, Hamamatsu University School of Medicine, 3600 Handa chou, Hamamatsu, Shizuoka 431-3192, Japan.
Brain Res Dev Brain Res. 2001 Feb 28;126(2):137-45. doi: 10.1016/s0165-3806(00)00137-1.
Developmental expressions of GABA transporters 1 and 3 (GAT1 and GAT3) were investigated in the rat olfactory bulb by using in situ hybridization histochemistry. We found that the expression of GAT1 and GAT3 mRNAs was dramatically changed in the granule cell layer (GCL), external plexiform layer (EPL) and glomerular layer (GL) during postnatal development. Among bulbar neurons, granule cells and periglomerular cells are GABAergic and they are localized in the GCL and GL, respectively. In the EPL, granule cells make GABAergic synapses with mitral cell dendrites. Thus, the changes seen in the GCL, EPL and GL seemed related to the development of the GABAergic system in the olfactory bulb. On the whole, our results demonstrated that expression patterns of GAT1 and GAT3 mRNAs have become similar to adult patterns on postnatal day 14 (P14), suggesting that GABA transporters may play a pivotal role in GABAergic neurotransmission after P14. However, expression patterns of GAT1 and GAT3 mRNAs in early postnatal days were quite distinct from those in adulthood. For example, in the GCL, immature granule cells already exhibited strong levels of GAT1 mRNA on P1 and the expression level was higher than that of granule cells in adulthood. GAT3 mRNA was strongly expressed in presumable radial glial cells surrounding the subependymal layer. In the EPL, few signals for the two transcripts were detected on P1 but they were markedly increased by P14. Our results indicate that GAT1 and GAT3 may play important roles in the development of the GABAergic system in the olfactory bulb.
采用原位杂交组织化学方法，研究了大鼠嗅球中γ-氨基丁酸转运体1和3（GAT1和GAT3）的发育表达情况。我们发现，在出生后发育过程中，GAT1和GAT3 mRNA的表达在颗粒细胞层（GCL）、外丛状层（EPL）和肾小球层（GL）中发生了显著变化。在嗅球神经元中，颗粒细胞和球周细胞是γ-氨基丁酸能的，它们分别位于GCL和GL中。在EPL中，颗粒细胞与二尖瓣细胞树突形成γ-氨基丁酸能突触。因此，在GCL、EPL和GL中观察到的变化似乎与嗅球中γ-氨基丁酸能系统的发育有关。总体而言，我们的结果表明，GAT1和GAT3 mRNA的表达模式在出生后第14天（P14）已变得与成年模式相似，这表明γ-氨基丁酸转运体可能在P14后γ-氨基丁酸能神经传递中起关键作用。然而，出生后早期GAT1和GAT3 mRNA的表达模式与成年期有很大不同。例如，在GCL中，未成熟的颗粒细胞在P1时就已表现出高水平的GAT1 mRNA，且表达水平高于成年期的颗粒细胞。GAT3 mRNA在室管膜下层周围的推测放射状胶质细胞中强烈表达。在EPL中，P1时未检测到这两种转录本的信号，但到P14时它们显著增加。我们的结果表明，GAT1和GAT3可能在嗅球γ-氨基丁酸能系统的发育中起重要作用。
