Neuroendocrine Actions of Androgens in Female Reproduction

 描述(申请人提供)：雄激素受体信号对正常的女性生殖至关重要，高雄激素血症是多囊卵巢综合征(PCOS)生殖中断的一个基本方面。雄激素受体缺乏或雄激素过多都会干扰正常排卵和女性生殖的神经内分泌控制，但这些影响的机制尚不清楚。我们的总体假设是：1)作用于大脑和垂体的雄激素在调节正常女性生育能力方面起着重要作用；2)过多的雄激素通过作用于下丘脑和垂体的雄激素受体，导致PCOS的神经内分泌特征：高黄体生成素、低卵泡刺激素和孕酮抵抗。我们将在三个独立但相互关联的目标上测试这些假设，这些目标集中在生理性雄激素信号和下丘脑和垂体中雄激素过剩的作用，使用遗传和雄激素过剩的小鼠模型相结合。这些方法将利用正常雌性小鼠和一种新的肥胖多囊卵巢综合征小鼠模型中特定细胞类型的雄激素和P4信号的遗传操作。目标1将通过评估雄激素受体(AR)是否对正常的女性生殖和雄激素过量的有害影响的神经元具有特异性，来关注大脑。利用Cre-loxP技术，AR将被选择性地从脑神经元中删除，随后特别是从Kispeptin神经元中删除。在新的PCOS小鼠模型中，这些神经元中缺乏AR的雌性将被研究对雄激素过剩的影响的抵抗力。目标2将重点放在脑垂体，假设过量的雄激素直接作用于促性腺激素，失调女性促黄体生成素β和促性腺激素β和促性腺激素的分泌。在PCOS小鼠模型中，将研究性腺激素选择性缺乏的雌性小鼠的生殖功能和促性腺激素分泌的改变以及对过量雄激素的反应。我们将在一个创新的GnRH脉冲系统中使用原代垂体细胞来直接测试雄激素对基础脉冲和GnRH诱导的促黄体生成素和卵泡刺激素以及促性腺激素基因表达的作用。目的3将测试雄激素过量是否干扰下丘脑和垂体的P4反馈，因为多囊卵巢综合征女性的一个特征是P4反馈受损。我们将确定神经内分泌组织中的雄激素过多是否调节孕激素受体(PR)，以及过多雄激素的作用是否会损害P4反馈。然后，我们将有选择地从脑神经元、Kispeptin神经元或垂体促性腺激素中去除PR，以调查哪些细胞介导P4负反馈以及雄激素过量引起的变化。总而言之，这些目标将阐明AR和PR在正常女性生殖的神经内分泌系统中的作用，并阐明过量雄激素在神经内分泌控制生殖失调中的作用。

 DESCRIPTION (provided by applicant): Androgen receptor signaling is crucial for normal female reproduction and hyperandrogenemia is a fundamental aspect of the reproductive disruption seen in Polycystic Ovary Syndrome (PCOS). Either lack of androgen receptor or androgen excess disrupts normal ovulation and neuroendocrine control of female reproduction, but the mechanisms for these effects are unknown. Our overall hypotheses are: 1) androgens acting in the brain and pituitary play an important role in regulating normal female fertility, and2) excess androgens, acting through androgen receptor in the hypothalamus and pituitary, are responsible for the neuroendocrine hallmarks of PCOS: high LH, low FSH, and progesterone (P4) resistance. We will test these hypotheses in a series of three independent but interrelated Aims that focus on the role of physiological androgen signaling and androgen excess in the hypothalamus and pituitary, using a combination of genetic and androgen-excess mouse models. Approaches will utilize genetic manipulation of androgen and P4 signaling in specific cell types in normal female mice and in a novel mouse model of obese PCOS. Aim 1 will focus on the brain by assessing whether androgen receptor (AR) is required specifically in neurons for normal female reproduction and for the deleterious effects of androgen excess. Using Cre-loxP technology, AR will be selectively deleted from brain neurons, and subsequently specifically from kisspeptin neurons. Females lacking AR in these neurons will be investigated for resistance to the effects of androgen excess in the new PCOS mouse model. Aim 2 will focus on the pituitary, with the hypothesis that excess androgens act directly at the gonadotrope to dysregulate LHβ and FSHβ and gonadotropin secretion in females. Female mice lacking AR selectively in the gonadotrope will be studied for altered reproductive function and gonadotropin secretion and in response to excess androgens in the PCOS mouse model. We will use primary pituitary cells in an innovative GnRH pulse system to directly test the actions of androgens on basal and GnRH-induced pulses of LH and FSH and gonadotropin gene expression. Aim 3 will test whether androgen excess interferes with P4 feedback at the hypothalamus and pituitary, as one attribute of PCOS women is impaired P4 feedback. We will determine if progesterone receptor (PR) is regulated by androgen excess in neuroendocrine tissues and whether P4 feedback is impaired by the actions of excess androgens. We will then remove PR selectively from brain neurons, kisspeptin neurons, or pituitary gonadotropes to investigate which cells mediate P4 negative feedback and the alterations caused by androgen excess. Together, these Aims will elucidate the role of AR and PR in the neuroendocrine system in normal female reproduction and illuminate the role of excess androgens in the dysregulation of neuroendocrine control of reproduction.