Photoperiodic Changes in Aggression

大多数动物在一年中的不同季节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，这使得它们能够应对季节性变化。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，生活在像夏天一样长的白天的动物会保持较高的睾丸素水平，因此会继续繁殖，而居住在像冬天一样短的白天的动物会因为睾酮水平低而抑制它们的繁殖。此外，最近有研究表明，尽管睾丸激素水平较低，但与长期饲养的啮齿动物相比，短期饲养的啮齿动物表现出更强的攻击性。考虑到睾丸激素调节攻击性的传统观念，这一发现特别有趣。该项目的目标是研究调节啮齿动物攻击性季节性变化的激素机制。具体地说，动物将被关在实验室的长或短白天，并将检测特定荷尔蒙的水平，包括雄激素DHEA和褪黑素。然后，攻击性将被录像，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，预测短白天会增加攻击性，脱氢表雄酮和褪黑素都在调节季节性攻击性方面发挥作用。这些实验挑战了一种简单的观念，即所有形式的攻击行为都是睾丸素依赖的，对于研究荷尔蒙如何作用于大脑以调节社交行为，以及这些行为可能如何被环境改变具有重要意义。总而言之，这些研究将有助于确定荷尔蒙控制攻击性的重要和新机制。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，提供极好的机会，获得实践经验，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.