Neuroendocrine mechanisms mediating differences in reproductive timing.

所有的动物在它们的一生中都使用来自环境的外部线索来决定什么行为该做，什么不该做。最终是大脑必须做出决定。这些暗示意味着什么以及如何回应。这项研究的目的是了解大脑如何整合不同类型的环境线索来调节繁殖的时间。研究人员将利用吊带蛇来研究温度线索如何刺激生殖活动的神经调节。在这些研究中，吊带蛇特别健壮，因为它的繁殖行为完全由温度调节。此外，从加拿大到墨西哥湾，从东海岸到西海岸，它是北美所有变温动物中分布范围最广的动物之一。因此，吊带蛇提供了一个相对简单但强大的框架来理解为什么（以及如何）动物对相同的环境线索做出不同的反应。具体来说，这个项目使用分子、生理和行为方法的结合来确定温度诱导的生殖行为是否受大脑内甲状腺激素代谢变化的调节。本计划将扩大本科生在科学教育和推广方面的参与，以提高社会的科学能力为最终目标。其他广泛的影响包括培养不同的学生在综合研究、批判性思维和社区参与方面的能力。该项目将测试一个假设，即温度诱导的生殖轴激活是由神经甲状腺激素代谢控制的。本研究将结合原位杂交、免疫组织化学、药理学操作、放射免疫测定和行为测试来实现以下具体目标：(1)确定低温休眠对神经内分泌GnRH系统的影响；(2)确定温度诱导的生殖行为是否受下丘脑内甲状腺激素代谢变化的调节；(3)确定生殖调节机制的温度敏感性变化是否介导了生殖时间的差异。该项目将促进对生殖时间可塑性的神经生物学基础的理解，并揭示可能受气候变化影响的机制。本项目的数据将用于生成课堂探究性学习模块，从而为学生提供实验设计、数据分析和数据解释方面的动手实践。

All animals use external cues from the environment throughout their lives to determine what behavior to do and not do. Ultimately it is the brain that must ?decide? what the cues mean and how to respond. The goal of this study is to understand how the brain integrates different types of environmental cues to regulate the timing of reproduction. The researcher will accomplish this using the garter snake to examine how temperature cues stimulate neural regulation of reproductive activity. Garter snakes are especially robust for these studies because its reproductive behavior is regulated exclusively by temperature. Furthermore, Thamnophis sirtalis has one of the most extensive ranges of any ectotherm in North America, from Canada to the Gulf of Mexico and from east to west coasts. Thus, garter snakes provide a relatively simple yet powerful framework for understanding why (and how) animals respond differently to the same environmental cues. Specifically this project uses a combination of molecular, physiological, and behavioral approaches to determine if temperature-induced reproductive behavior is regulated by changes in thyroid hormone metabolism within the brain. This project will broaden the participation of undergraduates in science education and outreach, with the ultimate goal of improving the scientific aptitude of the community. Additional broad impacts include training diverse students in integrative research, critical thinking, and community engagement.The project will test the hypothesis that temperature-induced activation of the reproductive axis is controlled by neural thyroid hormone metabolism. The research will use a combination of in situ hybridization, immunohistochemistry, pharmacological manipulation, radioimmunoassay, and behavioral testing to accomplish the following specific aims: (1) Identify the influence of low temperature dormancy on the neuroendocrine GnRH system; (2) Determine if temperature-induced reproductive behavior is regulated by changes in thyroid hormone metabolism within the hypothalamus; and (3) Determine if variation in the temperature sensitivity of reproductive regulatory mechanisms mediates differences in reproductive timing. This project will advance the understanding of the neurobiology underlying plasticity in reproductive timing, and should reveal mechanisms that may be impacted by climate change. Data from this project will be used to generate inquiry-based learning modules for the classroom, thereby providing students with hands-on practice in experimental design, data analysis and data interpretation.