Department of Anatomy, Histology and Embryology, K. K. Leung Brain Research Centre, Fourth Military Medical University Xi'an, China.
Department of Morphological Neural Science, Graduate School of Medical Sciences, Kumamoto University Kumamoto, Japan.
Front Neuroanat. 2013 Dec 9;7:42. doi: 10.3389/fnana.2013.00042. eCollection 2013.
Despite the abundance of studies on γ-aminobutyric acid (GABA) ergic neuron distribution in the mouse developing spinal cord, no investigation has been devoted so far to their birthdates. In order to determine the spinal neurogenesis of a specific phenotype, the GABAergic neurons in the spinal cord, we injected bromodeoxyuridine (BrdU) at different developmental stages of the glutamic acid decarboxylase (GAD)67-green fluorescent protein (GFP) knock-in mice. We thus used GFP to mark GABAergic neurons and labeled newly born cells with the S-phase marker BrdU at different embryonic stages. Distribution of GABAergic neurons labeled with BrdU was then studied in spinal cord sections of 60-day-old mice. Our birthdating studies revealed that GABAergic neurogenesis was present at embryonic day 10.5 (E10.5). Since then, the generation of GABAergic neurons significantly increased, and reached a peak at E11.5. Two waves for the co-localization of GABA and BrdU in the spinal cord were seen at E11.5 and E13.5 in the present study. The vast majority of GABAergic neurons were generated before E14.5. Thereafter, GABA-positive neuron generation decreased drastically. The present results showed that the birthdates of GABAergic neurons in each lamina were different. The peaks of GABAergic neurogenesis in lamina II were at E11.5 and E13.5, while in lamina I and III, they were at E13.5 and E12.5, respectively. The present results suggest that the birthdates of GABAergic neurons vary in different lamina and follow a specific temporal sequence. This will provide valuable information for future functional studies.
尽管已有大量研究探讨了γ-氨基丁酸（GABA）能神经元在发育中鼠脊髓中的分布，但迄今为止，尚无研究致力于确定其出生时间。为了确定特定表型的脊髓神经发生，我们在谷氨酸脱羧酶（GAD）67-绿色荧光蛋白（GFP）基因敲入小鼠的不同发育阶段注射了溴脱氧尿苷（BrdU）。因此，我们使用 GFP 标记 GABA 能神经元，并在不同的胚胎阶段用 S 期标记物 BrdU 标记新出生的细胞。然后在 60 日龄小鼠的脊髓切片中研究用 BrdU 标记的 GABA 能神经元的分布。我们的出生时间研究表明，GABA 能神经发生发生在胚胎第 10.5 天（E10.5）。从那时起，GABA 能神经元的产生显著增加，并在 E11.5 达到高峰。在本研究中，在 E11.5 和 E13.5 可见两个波的脊髓中 GABA 和 BrdU 的共定位。绝大多数 GABA 能神经元是在 E14.5 之前产生的。此后，GABA 阳性神经元的产生急剧减少。本研究结果表明，各层 GABA 能神经元的出生时间不同。II 层 GABA 能神经发生的高峰在 E11.5 和 E13.5，而在 I 层和 III 层，它们分别在 E13.5 和 E12.5。本研究结果表明，GABA 能神经元的出生时间在不同的层中不同，并遵循特定的时间顺序。这将为未来的功能研究提供有价值的信息。
