Chen XiaoNing, Li Jia, Zeng Lei, Zhang XueBo, Lu XiaoHua, Zuo MingXue, Zhang XinWen, Zeng ShaoJu
Beijing Key Laboratory of Gene Resource and Molecular Development, Beijing Normal University, Beijing, China.
Beijing Key Laboratory of Gene Resource and Molecular Development, Beijing Normal University, Beijing, China; College of Life Sciences, Hainan Normal University, Haikou, China.
PLoS One. 2015 May 4;10(5):e0125802. doi: 10.1371/journal.pone.0125802. eCollection 2015.
Birdsongs and the regions of their brain that control song exhibit obvious sexual differences. However, the mechanisms underlying these sexual dimorphisms remain unknown. To address this issue, we first examined apoptotic cells labeled with caspase-3 or TUNEL in Bengalese finch song control nuclei - the robust nucleus of the archopallium (RA), the lateral magnocellular nucleus of the anterior nidopallium (LMAN), the high vocal center (HVC) and Area X from post-hatch day (P) 15 to 120. Next, we investigated the expression dynamics of pro-apoptotic (Bid, Bad and Bax) and anti-apoptotic (Bcl-2 and Bcl-xL) genes in the aforementioned nuclei. Our results revealed that the female RA at P45 exhibited marked cell apoptosis, confirmed by low densities of Bcl-xL and Bcl-2. Both the male and female LMAN exhibited apoptotic peaks at P35 and P45, respectively, and the observed cell loss was more extensive in males. A corresponding sharp decrease in the density of Bcl-2 after P35 was observed in both sexes, and a greater density of Bid was noted at P45 in males. In addition, we observed that RA volume and the total number of BDNF-expressing cells decreased significantly after unilateral lesion of the LMAN or HVC (two areas that innervate the RA) and that greater numbers of RA-projecting cells were immunoreactive for BDNF in the LMAN than in the HVC. We reasoned that a decrease in the amount of BDNF transported via HVC afferent fibers might result in an increase in cell apoptosis in the female RA. Our data indicate that cell apoptosis resulting from different pro- and anti-apoptotic agents is involved in generating the differences between male and female song control nuclei.
鸟鸣及其大脑中控制鸣叫的区域呈现出明显的性别差异。然而，这些性别二态性背后的机制仍然未知。为了解决这个问题，我们首先在孟加拉雀的鸣叫控制核团——古纹状体粗核（RA）、前巢皮质外侧大细胞核（LMAN）、高级发声中枢（HVC）和X区，检查了从孵化后第15天（P15）到120天用半胱天冬酶-3或TUNEL标记的凋亡细胞。接下来，我们研究了上述核团中促凋亡基因（Bid、Bad和Bax）和抗凋亡基因（Bcl-2和Bcl-xL）的表达动态。我们的结果显示，P45时雌性RA表现出明显的细胞凋亡，这通过低水平的Bcl-xL和Bcl-2得以证实。雄性和雌性LMAN分别在P35和P45时出现凋亡峰值，并且观察到雄性的细胞损失更为广泛。在两性中均观察到P35后Bcl-2密度相应急剧下降，且雄性在P45时Bid密度更高。此外，我们观察到，在单侧损伤LMAN或HVC（支配RA的两个区域）后，RA体积和表达脑源性神经营养因子（BDNF）的细胞总数显著减少，并且与HVC相比，LMAN中更多的向RA投射的细胞对BDNF呈免疫反应性。我们推断，经由HVC传入纤维运输的BDNF量减少可能导致雌性RA中的细胞凋亡增加。我们的数据表明，由不同的促凋亡和抗凋亡因子导致的细胞凋亡参与了雄性和雌性鸣叫控制核团之间差异的形成。
