高级发声中枢（high vocal center，HVC）是鸣禽鸣唱运动通路和学习通路的共同起始核团，是发声控制系统的最高级中枢。有研究证明：HVC中的细胞是从附近的室管膜区（ventricular zone，VZ）迁移而来的。鸣禽在孵化15天以后，HVC中的神经元数量就开始表现出雌雄差异，但HVC中神经元数量变化的调控分子机制至今尚不清楚。通过基因查筛及实验室前期研究结果表明，Notch1 在HVC中的表达存在雌雄差异，并且在Notch1基因上存在雌激素应答元件（estrogen-responsive elements，EREs)，而雌激素在发声控制核团性双态的发育过程中发挥重要作用；Notch是一个在发育阶段起重要作用的调控分子，这些结果暗示，Notch基因可能参与了鸣禽发声控制核团神经元的早期发育调控。 本实验首先采用离体脑片培养技术，体外培养15日龄雄性斑胸草雀HVC区，体外培养两天，实验组加雌激素处理，对照组加DMSO处理，通过荧光实时定量PCR的方法检测实验组和对照组Notch1的 mRNA水平，结果显示：雌激素处理后，Notch1的 mRNA水平表达上升约1倍，说明Notch1 的表达受雌激素的调控。我们推测Notch1 在鸣禽性双态形成过程中可能发挥作用。针对这一问题，本论文进行了两方面的实验：一是在化学水平利用γ-分泌酶抑制剂DAPT，阻断Notch活化形式的形成，从而阻断Notch信号通路，来研究Notch1对VZ区细胞增殖以及对HVC区细胞分化的影响。已知DAPT是Notch活化过程中需要的一种蛋白水解酶；二是在基因水平阻断Notch1蛋白的合成，使其表达量降低，研究Notch1对VZ区细胞增殖以及对HVC区细胞分化的影响。本论文通过免疫组织化学的方法检测VZ区新生细胞的数量及HVC区神经元的数量。结果显示：降低Notch1的表达后，对VZ区新生细胞的数量没有影响，但可以抑制HVC区神经元的分化。由此我们推测，虽然Notch1基因对VZ区细胞增殖能力没有影响，但对HVC区神经元的分化是产生抑制作用的。

HVC is the initial nucleus in songbird song control nuclei.The neurons in HVC come from the VZ overlying the HVC.The number of neurons in HVC is different between males and females after posthatching 15 days. But the molecular mechanisms are not well clear.To data,Notch1 expression in HVC shows difference between males and females,and estrogen-responsive elements(EREs) are found in Notch1.Estrogen plays an important role during the sexual dimorphism of song control nuclei in songbird and Notch1 is an important molecular during development. Our experiment in vitro was to find the function of estrogen on Notch1 at postnatal 15 days in zebra finch. The result revealed that estrogen up-regulated Notch1 gene mRNA with real-time quantitative PCR method. So we speculated that Notch1 might play a role in the formation of sexual dimorphism in the songbird.To resolve this question, we designed two experiments: first,we blocked the formation of the activated form of Notch1 using DAPT，a proteolytic enzyme γ-secretase inhibitor，to prevent Notch signaling pathway on the chemical level,and to find the role of Notch1 on cell proliferation in VZ and cell differentiation in HVC. The second experiment was to block Notch1 protein synthesis on the mRNA level,and further investgated the role of Notch1 on cell proliferation in VZ and cell differentiation in HVC. Then we examined the number of new cells in VZ and the number of differentiated neurons in HVC with immunohistochemical method.The results showed that the decrease of the expression of Notch1 could not affect the number of new cells in VZ ,but inhibit the differentiated neurons in HVC. Therefore, we speculated that although the Notch1 had no effect on cell proliferation in VZ, but might take effect on neuron differentiation in HVC.