Neural Mechanisms Controlling Infant-Directed Behavior

描述(申请人提供)：保护和喂养幼小动物是生存所必需的。父母的照顾通常落在母亲身上，而女性往往自发地成为母亲。相比之下，男性表现出不同程度的父母互动，从攻击或忽视到完全养育后代。在老鼠身上，父亲的照顾需要促进：处女雄性通常攻击幼崽，只有在交配后才成为父亲。雄性在交配后12-18天左右表现出父母的行为。雄性小鼠对幼鼠的这种社会行为的转变为研究对幼鼠的相反社会反应背后的细胞机制提供了一个独特的范例。尽管我们的实验室最近发现了内侧视前区甘丙素表达神经元在对父母行为的积极调控中的关键作用，但涉及到对幼崽的这些社会反应的大脑区域的研究很少。我的项目旨在定义参与父母对幼崽行为的负面调控的神经群体，并了解影响这一行为的生理和环境因素。为了实现这一目标，我将首先确定位于穹隆周围区域的神经元的身份 在幼崽引导的激励性行为中被激活(目标1)。我将通过结合针对即刻早期基因c-fos的原位杂交和激光捕获显微镜技术来分离活跃神经元群体(目标1a)。这项实验将为行为相关的神经元群体提供潜在的候选标记。初步研究表明，urocortin 3 (Ucn3)是一个很有前途的候选基因，在穹隆周围区域有特定的表达，并在社会和应激相关行为中扮演有文献记载的角色。我将研究处女和交配的男性和女性穹隆周围ucn3细胞数量和基因表达水平的性别和经验依赖的调节(目标1b)。此外，我将通过比较男性和女性在各种社会活动中的活动来揭示穹隆周围ucn3细胞的行为特异性。 行为(目标1c)。为了从功能上测试穹隆周围ucn3神经元的作用，我将进行功能丧失和功能获得的实验(目标2)。我已经在实验室中复苏了一个在ucn3启动子下表达Cre重组酶的小鼠系，以促进使用条件病毒技术进行神经元特异性操作。我将使用Cre依赖的Capase 3病毒(Aim 2a)特异性地消融神经元，或者使用由设计药物方法(Aim 2b)独有激活的Cre依赖的兴奋性设计者受体来激活它们，以确定它们在幼鼠定向行为中的作用。最后，我将揭示穹隆周围ucn3细胞作为压力诱导的父母行为中断的媒介的作用(目标3)。首先，我将把穹隆周围ucn3细胞的激活与应激诱导的父母行为缺陷(Aim 3a)联系起来，然后试图通过使用一种表达突变的甘氨酸受体的Cre依赖病毒(Aim 3b)来抑制ucn3神经元，从而消除应激的这些行为影响。这些实验的总体目标是从功能上评估穹隆周围ucn3的作用。 神经元在父母行为负调控中的作用。此外，我的目标是了解这些神经元作为压力诱导的父母行为调节的中介所起的作用。这些研究将阐明参与基本社会行为的大脑回路，并提供新的切入点，为诊断和治疗与压力诱导的情绪变化相关的精神障碍提供信息。

DESCRIPTION (provided by applicant): Protection and feeding of young animals is essential for survival. Parental care typically falls to the mother and females are often spontaneously maternal. In contrast, males show varying levels of parental interactions ranging from attack or neglect to full parenting of offspring. In mice, paternal care requires facilitation: virgin males typically attack pups, becoming paternal only after mating. Males display parental behavior around 12-18 days after mating. This switch in the social behavior of male mice toward pups provides a unique paradigm to study cellular mechanisms underlying opposing social responses to pups. The brain areas involved in these social responses toward pups are poorly studied, though our lab has recently uncovered the critical role of galanin-expressing neurons of the medial preoptic area in the positive regulation of parental behavior. My project aims to define neural populations involved in the negative regulation of parental behavior toward pups and to understand physiological and environmental factors influencing this behavior. To accomplish this goal, I will first determine the identity of neurons located in the perifornical area that are activated during pup-directed agonistic behavior (Aim 1). I will isolate populations of active neurons by combining in situ hybridization against immediate early gene c-fos with laser capture microscopy techniques (Aim 1a). This experiment will provide potential candidate markers specific to behaviorally relevant neuron populations. Preliminary studies indicate that urocortin 3 (ucn3) is a promising candidate with specific expression in the perifornical area and a documented role in social and stress-related behaviors. I will study the sex- and experience-dependent modulation of perifornical ucn3 cell number and gene expression level in virgin and mated males and females (Aim 1b). Furthermore, I will uncover the behavioral specificity of perifornical ucn3 cells by comparing their activity in males and females during a variety of social behaviors (Aim 1c). To functionally test the role of perifornical ucn3 neurons, I will perform loss and gain-of-function experiments (Aim 2). I have resuscitated a mouse line expressing Cre recombinase under a ucn3 promoter in the lab to facilitate use of conditional viral techniques for neuron-specific manipulation. I will specifically ablate neurons using a Cre-dependent capase 3 virus (Aim 2a) or activate them using a Cre-dependent excitatory designer receptor exclusively activated by designer drug approach (Aim 2b) to determine their role in pup- directed behavior. Lastly, I will uncover the role of perifornical ucn3 cells as a mediator of stress-induced disruptions in parental behavior (Aim 3). First, I will correlate perifornical ucn3 cell activationwith stress- induced parental behavior deficits (Aim 3a) and then attempt to abrogate these behavioral effects of stress by inhibiting ucn3 neurons using a Cre-dependent virus expressing a mutated glycine receptor activated by a pharmacologically selective actuator molecule (Aim 3b). The overall goal of these experiments is to functionally assess the role of perifornical ucn3 neurons in the negative regulation of parental behavior. In addition, I aim to understand the role of these neurons as a mediator of stress-induced parental behavior modulation. These studies will illuminate brain circuits involved in essential social behaviors and provide new entry-points to inform the diagnosis and treatment of mental disorders associated with stress-induced mood alterations.