Developmental Regulation of Brain and Behavior

描述（申请人提供）：脊椎动物的大脑和行为存在性别差异。这些模型中的一些已经成为阐明调节神经结构和功能发育的机制的有力工具，因为它们允许对个体之间自然发生的差异进行受控调查，否则这些差异是高度相似的。这一战略需要仔细选择对特定问题和假设具有关键优势的模型系统。斑胸草雀的鸣叫系统非常适合研究神经结构和功能发育的分子基础，原因有很多，包括在任何易于处理的模型系统中最大的性别差异之一，以及与哺乳动物（包括人类）在调节社会行为的回路中的显著相似性。在这项建议中的实验将测试一个新的假设，即雌二醇（E2）与男性典型的性染色体基因表达水平的相互作用，以男性化的结构和功能的神经歌曲电路。虽然性类固醇在神经回路发育中的作用在许多模型系统中得到了很好的建立，但这些激素与其他对控制社会行为的大脑区域分化很重要的分子之间的相互作用在很大程度上是未知的。这项研究基于三个性染色体基因：分泌载体膜蛋白1（SCAMP 1）、分选连接蛋白2（SNX 2）和酪氨酸激酶B（脑源性神经营养因子BDNF的高亲和力受体）。与雌性相比，它们中的每一个在发育中的雄性的歌曲控制核中的表达增加。具体目标1将测试的假设，E2增加这些基因的表达或蛋白质编码的发展中的歌曲控制核内使用原位杂交和免疫组化。目的2将测试的假设，即基因的表达增强的歌曲系统的响应E2。将用E2处理孵化的雌性，并且在对形态分化和歌曲学习重要的特定发育阶段，将使用siRNA单独抑制SCAMP 1、SNX 2和trkB的表达。将在接受雌激素合成抑制剂治疗的男性中进行平行研究。目的3将评估一组关于E2，去甲肾上腺素（NE），BDNF和三个性染色体基因（trkB，SCAMP 1和SNX 2）的作用的机制假设。具体来说，我们将测试的想法，NE和/或BDNF的配体增加E2在歌曲系统分化使用操作平行于那些在具体目标1。我们还将确定NE和BDNF对形态发育和歌曲学习的影响，通过在适当的发育阶段抑制它们。第三项研究将使用siRNA来抑制SCAMP 1，以测试它是否有助于NE释放到鸣唱核中。最后，siRNA后放射自显影将用于确定SNX 2是否通过增加膜受体的可用性来增强BDNF和/或NE在歌曲系统中起作用的能力。 公共卫生相关性：拟议的工作是特别相关的NIMH的使命，并将阐明与神经回路的发展与一套明确的行为功能-学习和生产的主要手段，社会互动，语音通信的因素。这些研究将确定基因及其产物影响这种神经回路的结构和功能成熟的机制，重点是与类固醇激素和神经递质相互作用的潜力。因此，这些实验将增加对大脑形态和行为正常发育的关键因素的理解，并可能导致发现问题的解决方案，包括与自闭症，精神分裂症和抑郁症等心理健康障碍相关的问题。

DESCRIPTION (provided by applicant): Sex differences in brain and behavior exist across vertebrates. Several of these models have become powerful tools for elucidating mechanisms regulating development of neural structure and function, because they allow controlled investigation of naturally occurring differences among individuals that are otherwise highly similar. This strategy requires the careful selection of model systems with key advantages for particular questions and hypotheses. The zebra finch song system is ideally suited to study the molecular basis of development of neural structure and function for many reasons, including one of the largest sex differences in any tractable model system and remarkable similarity to mammals, including humans, in the circuitry regulating social behaviors. Experiments in this proposal will test a novel hypothesis, that estradiol (E2) interacts with male-typical levels of sex chromosome gene expression to masculinize structure and function of the neural song circuit. While the roles of sex steroids in development of neural circuitry are well established for many model systems, interactions between these hormones and other molecules important for differentiation of brain regions controlling social behaviors are largely unknown. The proposed studies are based on three sex chromosome genes: Secretory carrier membrane protein 1 (SCAMP1), sorting nexin 2 (SNX2), and tyrosine kinase B (the high affinity receptor for brain derived neurotrophic factor, BDNF). Expression of each of them is increased in song control nuclei of developing males compared to females. Specific Aim 1 will test the hypothesis that E2 increases expression of these genes or the proteins they encode within developing song control nuclei using in situ hybridization and immunonistochemistry. Aim 2 will test the hypothesis that expression of the genes enhances responsiveness of the song system to E2. Hatchling females will be treated with E2, and at specific stages of development important for morphological differentiation and song learning, siRNA will be used to individually inhibit expression of SCAMP1, SNX2 and trkB. Parallel studies will be done in males, treated with an estrogen synthesis inhibitor. Aim 3 will evaluate a set of mechanistic hypotheses regarding the roles of E2, norepinephrine (NE), BDNF, and the three sex chromosome genes (trkB, SCAMP1 and SNX2). Specifically, we will test the ideas that the ligands NE and/or BDNF are increased by E2 during song system differentiation using manipulations parallel to those in Specific Aim 1. We will also determine effects of NE and BDNF on morphological development and song learning by inhibiting them during appropriate developmental stages. A third study will use siRNA to inhibit SCAMP1 to test whether it facilitates release of NE into song nuclei. Finally, siRNA followed by autoradiography will be employed to determine whether SNX2 enhances the ability of BDNF and/or NE to act in the song system by increasing the availability of membrane receptors. PUBLIC HEALTH RELEVANCE: The proposed work is particularly relevant to the mission of NIMH, and will elucidate factors associated with development of a neural circuit with a clear set of behavioral functions -- the learning and production of a primary means of social interaction, vocal communication. The studies will determine mechanisms by which genes and their products influence the maturation of the structure and function of this neural circuit, focusing on the potential for interaction with steroid hormones and neurotransmitters. The experiments will therefore increase the understanding of factors critical to normal development of brain morphology and behavior, and can lead to the discovery of solutions to problems, including those associated with mental health disorders such as autism, schizophrenia and depression.