Photoperiodic Changes in Aggression

大多数动物在一年中的四季中都会经历环境条件的大幅波动。因此，许多动物在生理和行为上表现出季节性变化，这使它们能够科普季节性变化。日长是动物用来协调季节性行为和生理反应的主要环境线索。例如，动物生活在长“夏季”的一天长度将保持高水平的激素睾酮，从而将继续繁殖，而动物生活在短“冬季”的一天将抑制他们的繁殖由于低睾酮。 此外，最近的研究表明，尽管睾酮水平较低，但与长日饲养的动物相比，短日饲养的啮齿动物表现出更强的攻击性。考虑到睾酮调节攻击性的传统观念，这一发现特别有趣。本项目的目的是研究调节啮齿动物攻击性季节性变化的激素机制。具体而言，动物将在实验室中以长或短的天数圈养，并将检查特定激素的水平，包括雄激素DHEA和褪黑激素。然后将对攻击行为进行录像，并使用基于计算机的视频分析系统进行量化。根据以前的研究，预测短日照会增加攻击性，DHEA和褪黑激素在调节季节性攻击性方面都起作用。这些实验挑战了所有形式的攻击都依赖于睾丸激素的简单概念，并对研究激素如何作用于大脑以调节社会行为以及这些行为如何被环境改变具有重要意义。总的来说，这些研究将有助于确定重要的和新的激素控制攻击的机制。重要的是，这些研究将为研究生和本科生，包括代表性不足的少数群体，提供获得实践经验的绝佳机会，并使他们能够通过开展，介绍和发表科学研究来发展重要的科学技能。

Most animals experience large fluctuations in environmental conditions across the seasons of the year. Consequently, many animals display seasonal changes in physiology and behavior which allow them to cope with seasonal changes. Day length is the main environmental cue used by animals to coordinate seasonal behavioral and physiological responses. For example, animals living in long "summer-like" day lengths will maintain high levels of the hormone testosterone and thus will continue to breed, whereas animals housed on short "winter-like" days will inhibit their breeding due to low testosterone. In addition, it has recently been demonstrated that rodents housed in short days display increased aggression compared with animals housed on long days, despite lower levels of testosterone. This finding is particularly interesting given the traditional belief that testosterone regulates aggression. The goal of this project is to investigate the hormone mechanisms regulating seasonal changes in aggression in rodents. Specifically, animals will be housed in long or short days in the lab and levels of specific hormones, including the androgen DHEA and melatonin, will be examined. Aggression will then be videotaped and quantified using a computer-based video analysis system. Based on previous research, it is predicted that the short days will increase aggression and that both DHEA and melatonin play a role in mediating seasonal aggression. These experiments challenge the simple notion that all forms of aggression are testosterone-dependent and have important implications for the study of how hormones act on the brain to regulate social behaviors and how these behaviors may be altered by the environment. Collectively, these studies will help identify important and novel mechanisms of hormonal control of aggression. Importantly, these studies will provide excellent opportunities for both graduate and undergraduate students, including under-represented minorities, to gain hands-on experience and to allow them to develop important scientific skills by conducting, presenting and publishing scientific research.