Integration and independence of neuroendocrine mechanisms of behavior

描述(由申请人提供)：本建议中描述的研究的首要目标是描述从基因/蛋白质到激素再到行为、个体之间和性别之间的多个生物组织层次上行为的神经内分泌机制的整合程度。这项拟议的研究将探索这些组织水平之间的协变，重点是攻击性和性类固醇激素。以前的研究提供了对类固醇作用的确切理解，但对于这些组织水平如何在个人内部相互作用，导致特定的行为结果，留下了很大的不确定性。尤其令人惊讶的是，关于类固醇激素结合分子在大脑中的表达是否可以预测个体水平上的行为差异，令人惊讶的是，鲜为人知。同样不清楚的是，导致性别内部行为个体差异的机制是否在性别之间是相同的，即男性和女性使用相似或不同的机制来产生外表相似的行为的程度。拟议的研究物种是一种鸣禽，黑眼睛的Junco(Junco Hyemalis)，这是理想的，因为现有的广泛知识对睾酮(T)对个体之间和性别之间的行为差异的影响。这项研究将采用实验和观察的方法，通过量化激素敏感神经靶标(雄激素受体，AR；雌激素受体，ER；以及将T转化为雌二醇(E2)的芳香酶ARO)的蛋白质和mRNA，跨越各种行为相关的神经基因座。总的来说，神经系统的方法被用来解决两个特定的目标：(1)识别个体的攻击性程度、其循环T和E_2水平及其AR、ER和ARO的神经表达之间的协变模式。这一目的是通过分析自由生活受试者的攻击性，并使用定量聚合酶链式反应将他们的行为与循环激素水平和神经类固醇靶标的mRNA进行比较来实现的。(2)比较男性和女性是否使用相似的类固醇介导的攻击机制。这一目标是通过使用第一项研究的数据来对比男性和女性之间的目标行为关系来实现的。第二项研究更深入，使用免疫细胞化学来识别特定神经回路中的性别差异，在该回路中，一个类固醇靶点(ARO)介导攻击。ARO介导的攻击性将通过在攻击性试验后立即与早期基因产物Fos共同定位ARO来量化。这项拟议的研究将解决行为神经内分泌学(个体差异)中的一个重要未知问题，然后将这一新方法扩展到性别比较。通过填补这些关键知识空白，这项研究将阐明行为的基本神经内分泌机制。因此，它将有助于为今后研究影响类固醇介导的健康问题的神经内分泌因素所需的基本知识奠定基础，包括性别和高暴力/攻击性行为障碍(如ADHD、品行障碍等)倾向的个体差异，或改进相关神经缺陷的治疗。 与公共健康相关：通过确定个体水平上公开攻击行为变异的遗传和细胞因素，并在男性和女性之间比较这些神经内分泌机制，这项研究填补了关于基本生物行为机制的未解决的知识空白。因此，这些研究为今后在个体化治疗和预防影响儿童和所有年龄段的成年人的一些类固醇介导的行为障碍方面的进展奠定了基础。同样，识别不同地促进男性和女性攻击性的因素将增加对神经生物学和行为方面的根本性别差异的理解，并可能被应用于未来关于男性和女性攻击性倾向或其他荷尔蒙介导的健康问题的已知性别差异的原因/治疗的工作。

DESCRIPTION (provided by applicant): The overarching goal of the research described in this proposal is to characterize the degree of integration of neuroendocrine mechanisms of behavior at multiple levels of biological organization, from gene/protein to hormone to behavior, among individuals and between sexes. The proposed research will probe co-variation among these levels of organization, with a focus on aggression and sex steroid hormones. Previous research provides a firm understanding of steroid action, but leaves significant uncertainty about how these levels of organization interact with one another within an individual, leading to a specific behavioral outcome. In particular, surprisingly little is known as to whether the expression of steroid hormone-binding molecules in the brain predicts variation in behavior at the level of individuals. Also not clear is whether the mechanisms that lead to individual variability in behavior within a sex are shared between the sexes, i.e. the degree to which males and females use similar or different mechanisms to produce outwardly similar behaviors. The proposed study species is a songbird, the dark-eyed junco (Junco hyemalis), which is ideal owing to extensive existing knowledge of the effects of testosterone (T) on behavioral variation among individuals and between sexes. The research will employ both experimental and observational approaches by quantifying both protein and mRNA for steroid-sensitive neural targets (androgen receptor, AR; estrogen receptor, ER; and the enzyme aromatase, ARO, which converts T to estradiol, E2) across a diversity of behaviorally relevant neural loci. Collectively, a neural systems approach is used to address two specific aims: (1) To identify patterns of co-variation between an individual's degree of aggressiveness, its level of circulating T and E2 and its neural expression of AR, ER and ARO. This aim is achieved by assaying aggression in free-living subjects and comparing their behavior to circulating hormone levels and to mRNA for neural steroid targets, using quantitative PCR. (2) To compare whether males and females use similar steroid-mediated mechanisms of aggression. This aim is achieved by using data from the first study to contrast target-behavior relationships between males and females. A second study dives deeper, using immunocytochemistry to identify sex differences in the specific neural circuitry in which one steroid target (ARO) mediates aggression. ARO-mediated aggression will be quantified by co- localizing ARO with the immediate early gene product Fos following an aggression trial. The proposed research will address a significant unknown in behavioral neuroendocrinology (individual variation), and then extend this novel approach to sex comparisons. By filling these key knowledge gaps, this research will illuminate fundamental neuroendocrine mechanisms of behavior. It will thus contribute to a foundation of basic knowledge needed for future research on neuroendocrine factors affecting steroid-mediated health issues, including sex and individual differences in the propensity for behavioral disorders with high levels of violence/ aggression (e.g. ADHD, conduct disorder, etc.), or improved treatments of related neural deficiencies. PUBLIC HEALTH RELEVANCE: By identifying the genetic and cellular factors that underlie variability in overt aggression at the individual level and comparing these neuroendocrine mechanisms between males and females, this research fills unresolved knowledge gaps about basic biobehavioral mechanisms. These studies thus lay the groundwork for future advances in the individualized treatment and prevention of a number of steroid-mediated behavioral disorders affecting children and adults of all ages. Likewise, the identification of factors that differentially promote aggression in males and females will increase understanding of fundamental sex differences in neurobiology and behavior, and could be applied to future work on the causes/treatment of known sex differences in aggressive tendencies or other hormone-mediated health issues in men and women.