Function and Organization of Gonadotropin-Releasing Hormone Neuronal Circuitry

促性腺激素释放激素神经元回路的功能和组织

• 批准号: 9121095
• 负责人: Tova Berg
• 金额: $ 3.47万
• 依托单位: UNIVERSITY OF MICHIGAN AT ANN ARBOR
• 依托单位国家: 美国
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-09-23 至 2020-09-22
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9121095
• 关键词: Action Potentials; Address; Adult; Affect; Afferent Neurons; Age; Androgenization; Androgens; Animal Model; Automobile Driving; Brain; Cells; Communication; Comprehension; Development; Disease; Electrophysiology (science); Elements; Estrous Cycle; Exposure to; Failure; Feedback; Female; Fertility; Follicle Stimulating Hormone; Frequencies; Genetic; Glutamates; Goals; Gonadotropin Hormone Releasing Hormone; Hormonal; Hormones; Hyperactive behavior; Hypothalamic structure; Immunofluorescence Immunologic; Immunohistochemistry; In Situ Hybridization; Individual; Infertility; KISS1 gene; Knowledge; Location; Luteinizing Hormone; Maps; Menstrual cycle; Mus; Neurobiology; Neurons; Neurosecretory Systems; Ovarian; Ovulation; Pathogenesis; Pathology; Pattern; Perinatal Exposure; Phenotype; Physicians; Physiologic pulse; Physiological; Pituitary Gland; Polycystic Ovary Syndrome; Population; Production; Rabies virus; Regulation; Reproduction; Scientist; Signal Transduction; Sodium Channel; Steroids; Synapses; Synaptic Transmission; System; Testing; Testosterone; Tetrodotoxin; Time; Tracer; Training; Viral; Whole-Cell Recordings; Woman; Work; base; density; gamma-Aminobutyric Acid; insight; male; neuron development; neuronal circuitry; neurotransmission; postsynaptic; prenatal; prenatal exposure; prepuberty; presynaptic; presynaptic neurons; public health relevance; recombinase; reproductive; reproductive function; research study; synaptogenesis; tool; transmission process; voltage

 DESCRIPTION (provided by applicant): Polycystic ovary syndrome (PCOS) is the most common cause of anovulatory infertility and is characterized by irregular menstrual cycles and elevated androgens. The central neuronal system that regulates downstream reproductive function communicates through gonadotropin-releasing hormone (GnRH) neurons. Shifts in GnRH pulse frequency during the normal menstrual cycle signal the pituitary to release hormones that regulate follicular maturation and ovarian steroid production. Hormonal feedback is conveyed to GnRH neurons through their afferent network, however the circuitry and activity of this network is not well understood. In most adult women with PCOS this neuronal system is persistently overactive leading to failure of ovulation and high androgen production. When this increased neuroendocrine activity begins is not known, however neuronal hyperactivity during development could result in altered network connectivity and function in adulthood. Exposure to elevated androgens during development results in phenotypes that are similar to PCOS in many species. Our hypothesis is that GnRH neuron activity during the prepubertal period is critical for attracting appropriate synaptic inputs and that prenatal androgenization (PNA) alters this activity and synaptogenesis and thus the adult connectivity and function of the GnRH neuronal circuitry. To test this hypothesis we will study how PNA alters the adult organization of the GnRH neuronal network and the function of afferent inputs to GnRH neurons during prepubertal development. In Aim 1 we will test the hypothesis that PNA increases the frequency and amplitude of GABAergic and glutamatergic postsynaptic currents (PSCs) to prepubertal GnRH neurons and that this occurs through an increased density of synaptic connections. Whole-cell electrophysiological recordings of PSCs will be made to examine the spontaneous function of these inputs during prepubertal development. Evoked activity will be used to identify synaptic connections that have been established but are not yet active. In Aim 2 we will test the hypothesis that developmental exposure to elevated androgens results in altered adult organization of the presynaptic network to GnRH neurons in females. We will utilize a viral tracer targeted to Cre recombinase-expressing GnRH neurons to map the circuitry of the GnRH neuronal network in combination with immunofluorescence and/or in situ hybridization to identify neuron phenotype. This will allow us to characterize the number, location and identify of GnRH neuron afferents and to examine if this connectivity is altered by developmental exposure to androgens. Both Aims will further our knowledge of typical GnRH neuron development beyond the study of individual neurons to comprehension of network interactions with great potential to address long-standing questions about hypothalamic regulation of fertility. They will also further our understanding of how PNA alters the GnRH neuronal network. The broad implications and intellectual depth of this project are essential elements for my training as a physician-scientist.

 描述（由申请人提供）：多囊卵巢综合症（PCOS）是无排卵性不孕的最常见原因，其特征是月经周期不规则和雄激素升高。调节下游生殖功能的中枢神经系统通过促性腺激素释放激素 (GnRH) 神经元进行通信。正常月经周期期间 GnRH 脉冲频率的变化会向垂体发出信号，释放调节卵泡成熟和卵巢类固醇产生的激素。激素反馈通过 GnRH 神经元的传入网络传递给 GnRH 神经元，但该网络的电路和活动尚不清楚。在大多数患有多囊卵巢综合症的成年女性中，这种神经元系统持续过度活跃，导致排卵失败和雄激素分泌过多。这种神经内分泌活动何时开始增加尚不清楚，但发育过程中的神经元过度活跃可能会导致成年后网络连接和功能的改变。在许多物种中，发育过程中暴露于升高的雄激素会导致与多囊卵巢综合症相似的表型。我们的假设是，青春期前的 GnRH 神经元活动对于吸引适当的突触输入至关重要，而产前雄激素化 (PNA) 会改变这种活动 和突触发生，从而影响 GnRH 神经元回路的成体连接和功能。为了检验这一假设，我们将研究 PNA 如何改变 GnRH 神经元网络的成人组织以及青春期前发育期间 GnRH 神经元传入输入的功能。在目标 1 中，我们将检验以下假设：PNA 增加青春期前 GnRH 神经元的 GABA 能和谷氨酸能突触后电流 (PSC) 的频率和幅度，并且这是通过增加突触连接密度来实现的。将进行 PSC 的全细胞电生理记录，以检查青春期前发育过程中这些输入的自发功能。诱发活动将用于识别已建立但尚未激活的突触连接。在目标 2 中，我们将检验以下假设：发育过程中暴露于升高的雄激素会导致女性 GnRH 神经元突触前网络的成年组织发生改变。我们将利用针对表达 Cre 重组酶的 GnRH 神经元的病毒示踪剂，结合免疫荧光和/或原位杂交来绘制 GnRH 神经元网络的电路图，以识别神经元表型。这将使我们能够表征 GnRH 神经元传入的数量、位置和识别，并检查这种连接是否会因发育过程中暴露于雄激素而改变。这两个目标都将进一步加深我们对典型 GnRH 神经元发育的了解，超越对单个神经元的研究，理解网络相互作用，具有解决下丘脑生育调节长期存在的问题的巨大潜力。它们还将进一步加深我们对 PNA 如何改变 GnRH 神经元网络的理解。这个项目的广泛影响和知识深度是我作为一名医师科学家接受培训的基本要素。