Early Life Experience Shapes Visceral Circuits

早期生活经验可以改变成年人的情绪和压力反应，但只有有限的研究探讨了经验如何塑造中枢神经回路的发展。我们预测，对早期生活经验的操纵将改变中枢内脏回路的功能组织，而改变的神经解剖学将与对压力事件的行为、生理和神经反应的改变相对应。拟议的研究将通过在成年雄性和雌性大鼠中进行实验来测试这一预测，这些大鼠的发育史是在出生后的前两周内每天短暂地进行15分钟（MS 15）或3小时（MS 180）的母体分离。未分离（MS 0）大鼠作为对照。作为年轻成年大鼠，将筛选所有大鼠在高架十字迷宫中的行为差异，并采集血样以记录束缚应激诱发的血浆皮质酮波动。目的1和2中的后续实验将在行为和行为筛选的成年大鼠中进行。目标1实验将检验以下假设：早期孕产妇护理（通过MS 15和MS 180操纵）与性别相互作用，以差异性地改变中央内脏回路的解剖特征。伪狂犬病病毒的逆行跨神经元转运将被用来探测不同发育史大鼠中枢自主神经回路的差异。在第二个实验中，经验依赖性的改变去甲肾上腺素（NA）的感觉通路将进行检查。为此，将在多巴胺β羟化酶启动子的控制下表达增强的绿色荧光蛋白的独特慢病毒载体显微注射到尾髓质中，以标记投射到下丘脑和边缘前脑的转染NA神经元的轴突主干。目的2实验将检验这一假设，即早期的母亲照顾与性别的相互作用，差异改变应激诱导的神经Fos激活中枢内脏电路节点。大鼠将在束缚、LiCl处理、捕食者气味暴露或匹配的对照处理后用固定剂灌注，以分析刺激诱导的延髓NA神经元及其中央投射野中的Fos表达。还将定量NA末端免疫标记密度和CRF/CRH标记，以确定性别和/或MS组差异是否相互作用。将在筛选试验中的行为和激素反应背景下分析和解释数据，并注意产后早期经历和性别对解剖和生理结局的预测影响。拟议的工作将推进我们的理解如何早期孕产妇护理可以改变男性和女性的中央内脏电路的发展轨迹，并将提供有关早期经验对成人情绪和压力反应的影响的新见解。婴儿与其母亲（或主要照顾者）之间的互动对于正常生长和发育至关重要，干扰可能会破坏后代的生理和行为功能。拟议的研究将使用大鼠的解剖学和生理学方法来测试这一假设，即早期生活事件对后来对压力和情绪事件的反应的影响与向大脑提供内脏感觉反馈并产生情绪表达的回路的发育可塑性有关。

DESCRIPTION (provided by applicant): Early life experience can alter adult emotionality and stress responsiveness, but only limited research has examined how experience shapes the development of central neural circuits. We predict that manipulation of early life experience will alter the functional organization of central visceral circuits, and that altered neuroanatomy will correspond with altered behavioral, physiological, and neural responses to stressful events. The proposed research will test this prediction by performing experiments in adult male and female rats with a developmental history of having been handled briefly for daily maternal separation of either 15 min (MS15) or 3 hr (MS180) during the first two postnatal weeks. Non-separated (MS0) rats will serve as controls. As young adults, all rats will be screened for behavioral differences in the elevated plus maze, and blood samples will be collected to document restraint stress-evoked excursions in plasma corticosterone. Subsequent experiments in Aims 1 and 2 will be performed in behaviorally- and hormonally-screened adult rats. Aim 1 experiments will test the hypothesis that early maternal care (manipulated via MS15 and MS180) interacts with sex to differentially alter the anatomical features of central visceral circuits. Retrograde transneuronal transport of pseudorabies virus will be used to probe for differences in central autonomic circuits in rats with different developmental histories. In the second experiment, experience-dependent alterations in noradrenergic (NA) sensory pathways will be examined. For this, a unique lentivirus vector that expresses enhanced green fluorescent protein under the control of a dopamine beta hydroxylase promoter will be microinjected into the caudal medulla to label the axonal arbors of transfected NA neurons that project to the hypothalamus and limbic forebrain. Aim 2 experiments will test the hypothesis that early maternal care interacts with sex to differentially alter stressor-induced neural Fos activation in central visceral circuit nodes. Rats will be perfused with fixative after restraint, LiCl treatment, predator odor exposure, or matched control treatment for analyses of stimulus-induced Fos expression in medullary NA neurons and in their central projection fields. NA terminal immunolabeling density and CRF/CRH labeling also will be quantified to determine whether sex and/or MS group differences interact. Data will be analyzed and interpreted within the context of behavioral and hormonal responses in the screening tests, with attention paid to predicted effects of early postnatal experience and sex on anatomical and physiological outcomes. The proposed work will advance our understanding of how early maternal care can alter the developmental trajectory of central visceral circuits in males and females, and will provide new insights regarding the impact of early experience on adult emotionality and stress responsiveness. Interactions between infants and their mother (or primary caregiver) are critical for normal growth and development, and perturbations can disrupt physiological and behavioral functions in the offspring. The proposed research will use anatomical and physiological methods in rats to test the hypothesis that the influence of early life events on later responses to stress and emotional events is linked to developmental plasticity of circuits that provide visceral sensory feedback to the brain and generate emotional expression.