OXYTOCIN REGULATION BY NEUROSTEROIDS & GABA-A RECEPTOR

神经甾体激素对催产素的调节

• 批准号: 6521141
• 负责人: JANET A AMICO
• 金额: $ 26.66万
• 依托单位: UNIVERSITY OF PITTSBURGH AT PITTSBURGH
• 依托单位国家: 美国
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-04-01 至 2004-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6521141
• 关键词: GABA receptor; analog; antisense nucleic acid; autoradiography; behavioral /social science research tag; bicuculline; hormone biosynthesis; hormone regulation /control mechanism; hypothalamus; in situ hybridization; laboratory rat; lactation; maternal behavior; neuroendocrine system; oxytocin; pregnancy; pregnanolone; progesterone

Oxytocin(OT) is a nonapeptide that functions as both a hormone and a neuropeptide during certain reproductive processes and behaviors. OT is essential for milk ejection during lactation, enhances uterine contractility at parturition and induces maternal behavior in the rat. Maternal behavior in most mammals is stimulated by the hormonal milieu of late pregnancy. In the rat, rising levels of estrogen (E) superimposed on the late-term decline in progesterone (P), stimulate maternal behavior. The ovarian steroid exposure which optimally stimulate maternal behavior (declining P in the setting of E priming) also enhances levels of oxytocin (OT) mRNA and OT peptide in the paraventricular and supraoptic nuclei (PVN and SON) of the hypothalamus, which are the sites of synthesis of over 95% of the OT formed within the CNS. Progesterone plays a key role in the regulation of both maternal behavior and OT expression by mechanisms which are not well understood. P can affect neuronal transmission by binding to its cognate nuclear receptor (PR), which acts as a hormone- dependent transcription factor, or by binding to the membrane bound GABAA receptor complex. We hypothesize that changes in OT expression in the PVN and SON of the steroid-treated and pregnant rat are regulated by P-mediated plasticity in subunits of the GABAA receptor and/or by alterations in concentrations of neurosteroids. Increased OT expression within magnocellular and/or parvocellular neurons of the PVN may in turn facilitate the onset of maternal behavior. The specific aims of this proposal are as follows:1-administer allopregnanolone, or its agonist, ganaxolone, or inhibitors of allopregnanolone formation to the steroid-treated ovariectomized rat and measure changes in OT mRNA and OT peptide in the PVN and SON of the hypothalamus; 2-administer allopregnanolone or its agonist, ganaxolone, or block formation of allopregnanolone and measure indices of maternal behavior, hypothalamic OT mRNA and OT peptide in rats receiving a steroid treatment known to induce maternal behaviors and; 3-measure by in situ hybridization the relative abundance of OT mRNA and GABAA receptor subunit mRNAs and measure by in vitro receptor autoradiography 3[H]muscimol GABAA receptor binding in the hypothalami of the steroid- treated or allopregnanolone (ganaxolone)- treated ovariectomized rat and the pregnant or lactating rat; 4 - administer an antisense oligonucleotide to OT or an OT antagonist i.c.v. to the steroid-treated ovariectomized rat or the pregnant rat and measure indices of maternal behavior and levels of hypothalamic OT mRNA and OT peptide.

催产素 (OT) 是一种九肽，在某些生殖过程和行为中既充当激素又充当神经肽。 OT 对于哺乳期间的乳汁排出至关重要，可增强分娩时的子宫收缩力并诱导大鼠的母性行为。大多数哺乳动物的母性行为是受到妊娠后期荷尔蒙环境的刺激。在大鼠中，雌激素 (E) 水平的上升与孕激素 (P) 的后期下降相叠加，刺激了母性行为。卵巢类固醇暴露可以最佳地刺激母体行为（在 E 启动的情况下 P 下降）也会提高下丘脑室旁核和视上核（PVN 和 SON）中催产素 (OT) mRNA 和 OT 肽的水平，这些部位是超过 95% 的 OT 在 CNS 内合成。黄体酮在调节母体行为和 OT 表达方面发挥着关键作用，其机制尚不清楚。 P 可以通过与其同源核受体 (PR) 结合（充当激素依赖性转录因子）或通过与膜结合的 GABAA 受体复合物结合来影响神经元传递。我们假设，类固醇治疗和怀孕大鼠的 PVN 和 SON 中 OT 表达的变化受到 GABAA 受体亚基中 P 介导的可塑性和/或神经类固醇浓度变化的调节。 PVN 的大细胞和/或小细胞神经元内 OT 表达的增加可能反过来促进母性行为的发生。本提案的具体目的如下： 1-给激素处理的去势大鼠施用四氢孕酮或其激动剂加奈索酮或四氢孕酮形成抑制剂，并测量下丘脑PVN和SON中OT mRNA和OT肽的变化; 2-给予四氢孕酮或其激动剂加奈索酮，或阻断四氢孕酮的形成，并测量接受已知诱导母体行为的类固醇治疗的大鼠的母体行为指数、下丘脑OT mRNA和OT肽； 3-通过原位杂交测量 OT mRNA 和 GABAA 受体亚基 mRNA 的相对丰度，并通过体外受体放射自显影测量 3[H] 蝇蕈醇 GABAA 受体在类固醇治疗或四氢孕酮（加奈索酮）治疗的去势大鼠下丘脑中的结合以及怀孕或哺乳期的大鼠； 4-静脉内给予OT或OT拮抗剂反义寡核苷酸。给经过类固醇治疗的去势大鼠或怀孕大鼠，测量母体行为指标以及下丘脑 OT mRNA 和 OT 肽的水平。