DISSERTATION RESEARCH: Neuroendocrine Mechanisms of Seasonal Aggression in Female Siberian Hamsters (Phodopus sungorus)

攻击性是一种广泛的自然发生的行为，具有一系列适应性功能，包括获得配偶和资源。由性腺产生的性兴奋通常与高水平的攻击性有关。然而，在季节性繁殖的动物中，在睾丸激素水平无法检测到的非繁殖季节，侵略性可能既强烈又广泛。 这意味着，侵略是由一个以上的机制，并有很少的了解如何非繁殖侵略的调节。本研究以雌性西伯利亚仓鼠为模型，试图了解其攻击行为季节性变化的生理机制。这项工作是高度综合性的，与大多数其他研究不同，它将考虑许多相关的内分泌参数及其相互作用，以了解大脑和激素如何控制女性的季节性攻击。这些研究将为更广泛地了解调节攻击性和社会行为的生理机制提供重要的见解。此外，这项建议将允许继续指导本科生和高中生进行与这项工作直接相关的研究。这些研究成果的传播将包括公开讲座和科学会议，期刊文章，以及专门的区域研讨会和组织，重点是在科学领域发展代表性不足的少数民族。研究人员迄今为止的数据表明，褪黑激素，编码光周期的激素信号，驱动侵略的季节性变化，并进一步表明肾上腺激素，如脱氢表雄酮，而不是性腺激素，可能通过在动物非生殖期转化为活性雄激素或雌激素来间接调节攻击性。为了检查从性腺到肾上腺来源的激素的季节性转换，拟议的研究测试了DHEA介导非繁殖季节侵略的假设，褪黑激素调节DHEA的释放及其转化为活性激素，然后可以作用于神经受体。具体目标1将季节性变化的侵略和季节性褪黑激素的线索，神经受体配置文件（雄激素和雌激素受体）以及转换酶（芳香化酶，酶T转化为雌二醇），通过免疫细胞化学。具体目标2将确定DHEA水平的变化是否预测个人之间的侵略跨季节的挑战动物在不同的光周期与ACTH，并评估DHEA释放。最后，具体目标3将测试的假设，即短的一天增加褪黑激素介导的季节性变化的DHEA分离肾上腺从其他器官负责DHEA的释放，并通过使用体外生物测定，以解决本地化的行动褪黑激素对这个器官及其随后生产的DHEA。总的来说，拟议的工作采取了一个整体的有机体的方法，并检查多个组织的直接激素作用，以确定潜在的机制，在雌性仓鼠的季节性侵略使用多层次的分析。为了促进数据的正确存储和访问，手稿将在可能的情况下以开放获取的格式发表，并在实验室网站上发表。将在国际和国家会议上以及在当地场地向包括高中在内的普通观众作介绍。 在处理主要项目的样本后，样本将被存档，并可供相关方合作使用。最后，PI将与印第安纳州大学信息技术服务部门合作，将数据存档在研究数据综合体（RDC）上，这是一个专门用于托管数据库的服务器。

Aggression is a widespread naturally-occurring behavior serving a range of adaptive functions including access to mates and resources. Testosterone produced by the gonads is frequently associated with high levels of aggression. However, in seasonal breeding animals aggression can be both intense and widespread during the non-breeding season when testosterone levels are undetectable. This means that aggression is regulated by more than one mechanism and there is little understanding of how non-breeding aggression is regulated. This research seeks to understand the physiological mechanisms that underlie seasonal variation of aggression using female Siberian hamsters as a model. This work is highly integrative and unlike most other studies that examine single factors it will consider many relevant endocrine parameters and their interactions to understand how the brain and hormones function to control seasonal aggression in females. These studies will provide important insights into the physiological mechanisms mediating aggression, and social behavior more broadly. Additionally, this proposal will allow for the continued mentorship of undergraduates and high school students in research directly related to this work. Communication of these research findings will include public lectures and scientific conferences, and journal articles, as well as specialized regional symposia and organizations focused on the advancement of underrepresented minorities in the sciences.The researchers' data so far show that melatonin, the hormonal signal encoding photoperiod, drives seasonal changes in aggression, and further that adrenal hormones, such as DHEA, rather than gonadal hormones, may indirectly regulate aggression via conversion to active androgens or estrogens during periods when animals are non-reproductive. To examine seasonal switching from a gonadal to adrenal source of hormone, the proposed research tests the hypotheses that DHEA mediates non-breeding season aggression and that melatonin regulates DHEA release and its conversion to active hormones, which can then act on neural receptors. Specific Aim 1 will link seasonal changes in aggression and seasonal melatonin cues to neural receptor profiles (androgen and estrogen receptors) as well as a converting enzyme (aromatase, the enzyme that converts T to estradiol), via immunocytochemistry. Specific Aim 2 will determine whether changes in DHEA levels predict aggression among individuals across seasons by challenging animals in different photoperiods with ACTH, and assessing DHEA release. Lastly, Specific Aim 3 will test the hypothesis that short-day increases in melatonin mediate seasonal changes in DHEA by isolating the adrenal gland from other organs responsible for DHEA release and by using an in vitro bioassay to address localized action of melatonin on this organ and its subsequent production of DHEA. Collectively, the proposed work takes a whole organism approach and examines direct hormonal action on multiple tissues to determine the mechanisms underlying seasonal aggression in female hamsters using multiple levels of analysis. To facilitate proper storage and access of data, manuscripts will be published in open-access format, when possible, and on the lab website. Presentations will be made at international and national conferences, as well as in local venues to lay audiences, including high schools. Following processing of samples for the primary project, samples will be archived, and made accessible for collaborations from interested parties. Lastly, the PI will work with Indiana University Information Technology Services to archive data on the Research Data Complex (RDC), a dedicated server for hosting databases.