DISSERTATION RESEARCH: Neuroendocrine Mechanisms Underlying Rapid Change in Social Behavior

社会行为快速变化的神经内分泌机制（0206677）主要研究者：约翰·罗伯特·戈德温博士生：凯瑟琳·安妮·塞姆萨环境和内部生理影响影响包括人类在内的动物的性和攻击行为的表达。 对于生活在不可预测的环境中的物种来说，展示性行为和/或攻击行为的适当性可能会迅速改变。 大量的研究都集中在适应物理环境的变化，但社会环境同样是不可预测的，因此，动物能够在面对社会变化时迅速适应自己的行为也很重要。 在过去的二十年里，大量的工作已经证明了神经肽激素在调节社会行为中的重要作用，从交配和父母照顾到配偶守卫和领土防御。 两种神经肽激素被发现起着特别突出的作用，它们是在非哺乳动物脊椎动物中的精氨酸催产素（AVT）和在哺乳动物中发现的非常相似的精氨酸加压素（AVP）。 这些激素在大脑中释放，并改变已知与社会行为相关的区域的神经功能。 虽然许多研究已经表明这些激素对实验室行为的影响，但仍然有相对较少的研究了AVT或AVP在自然环境中影响性行为和攻击行为的详细机制。 这项研究将探讨AVT影响性行为和攻击行为的机制，以及决定这种激素对这些行为影响的性质的社会和激素条件。 实验模型是蓝头濑鱼（Thalassoma bifasciatum），这是一种经过充分研究的性别和角色改变的珊瑚礁鱼。 蓝头濑鱼表现出社会控制的雌性到雄性的性别变化，其中雌性可以在成为社会统治者的大约10天内变成功能性雄性。 这种模式物种有两个主要的优势，为类型的研究建议。 首先，性别变化过程对来自社会环境的线索的依赖性使其成为理解社会对神经功能的影响以及环境和内部激素线索在控制行为中的相互作用的一个非常好的系统。 其次，由于大量的人口在浅水，受保护的沃茨和非凡的容易捕捉标记和实验操作，蓝头鱼允许神经肽的行动机制进行研究的性质。 John Godwin先前的工作表明，当雌性开始表现出雄性行为，并且在性别转变期间卵巢变成睾丸时，下丘脑中的AVT表达增加。 凯瑟琳·塞姆萨（Katharine Semsar）和约翰·戈德温（John Godwin）的研究表明，AVT可以在没有领土的大型雄性中诱导领土攻击和求偶行为，而AVT受体阻断剂可以减少这些行为。 本提案中概述的研究将确定：i）AVT是否是女性在行为上变成男性所必需的，以及增加AVT是否可以加速这一过程，ii）通过这种激素的受体测量的对AVT的反应能力是否在性别改变期间发生变化，以及iii）在性别改变期间升高的有效雄激素（11-酮睾酮）对AVT及其受体在大脑中的表达的影响。 这项工作将提高我们对行为适应和神经肽激素在这些过程中的作用的理解。 这些机制具有很强的基本意义，但由于攻击性行为的社会成本，它们也更普遍地重要。

Neuroendocrine mechanisms underlying rapid change in social behavior (0206677)Principal Investigator: John Robert GodwinDoctoral Student: Katharine Anne SemsarBoth environmental and internal physiological influences affect the expression of sexual and aggressive behavior by animals including humans. For species that live in unpredictable environments, the appropriateness of displaying sexual and/or aggressive behavior can change quickly. A good deal of research has focused on adaptations to changes in the physical environment, but social environments can be equally unpredictable and it is therefore important that animals be able to adapt their behavior quickly in the face of social change as well. A large body of work over the past twenty years has documented important roles for neuropeptide hormones in mediating social behaviors ranging from mating and parental care to mate guarding and territorial defense. Two neuropeptide hormones found to play especially prominent roles are arginine vasotocin (AVT) in non-mammalian vertebrates and the very similar arginine vasopressin found in mammals (AVP). These hormones are released in the brain and act to alter neural function in areas known to be associated with social behavior. While many studies have shown effects of these hormones on behavior in the laboratory, there are still relatively few studies that have examined the detailed mechanisms by which AVT or AVP affect sexual and aggressive behavior in the full complexity of the natural environment. This study would explore mechanisms by which AVT affects sexual and aggressive behavior and the social and hormonal conditions that determine the nature of the effects of this hormone on these behaviors. The experimental model is the bluehead wrasse (Thalassoma bifasciatum), a well studied sex- and role-changing coral reef fish. Bluehead wrasses exhibit socially controlled female-to-male sex change in which females can become functional males within approximately ten days of becoming socially dominant. This model species has two principal advantages for the type of study proposed. First, the dependence of the sex change process on cues from the social environment makes it a very good system for understanding social influences on neural function and the interaction of environmental and internal hormonal cues in controlling behavior. Second, because of large populations in shallow, protected waters and extraordinary ease of capture for marking and experimental manipulations, bluehead wrasses allow the mechanisms underlying neuropeptide actions to be studied in nature. Previous work by John Godwin has shown that AVT expression increases in the hypothalamus as females begin to exhibit male behavior and their ovaries become testis during sex change. Studies by Katharine Semsar and John Godwin have shown that AVT can induce territorial aggression and courtship behavior in large males who do not hold territories while an AVT receptor blocker can reduce these behaviors in territory-holding males. The studies outlined in this proposal would determine: i) whether AVT is necessary for females to become males behaviorally and whether augmenting AVT can accelerate this process, ii) whether the ability to respond to AVT, as measured by receptors for this hormone, changes during sex change, and iii) what the effects of a potent androgenic hormone that rises during sex change (11-ketotestosterone) are on the expression of AVT and its receptor in the brain. This work should improve our understanding of behavioral adaptation and the role of neuropeptide hormones in these processes. These mechanisms are of strong basic interest, but also important more generally because of the societal costs of aggressive behavior.