REGULATION OF BRAIN NEUROPEPTIDE / RECEPTOR SYSTEMS

神经内分泌神经肽，如加压素、催产素和神经降压素，在哺乳动物的大脑中作为神经激素和神经递质。编码这些多肽的基因及其受体在大脑神经元中的表达受到雌激素、皮质类固醇和睾酮等类固醇激素的调节。该实验室多年来一直试图了解这种激素调节在这些神经肽系统功能中的重要性，并利用它们来了解类固醇对脑神经元神经递质基因转录的影响的细胞和分子事件。在神经母细胞瘤细胞、原代神经元培养以及大鼠和小鼠脑内收集的数据表明，雌激素不仅通过核激素受体二聚化和与共同的激素反应元件结合的“经典”作用机制发挥作用，而且还通过与其他依赖于蛋白激酶的信号转导途径(如蛋白激酶A和丝裂原激活的蛋白激酶)的“串扰”发挥作用。在这一更新申请中提出的研究将检验雌激素在体外和体内对神经肽基因表达的调节的假说。他们还将研究雌激素受体亚型(ERα和新发现的ERβ)在这些反应中的相对作用，这些反应涉及“经典”和蛋白激酶依赖的转录作用的混合。因此，正是这些效应的组合赋予了雌激素等激素对大脑的戏剧性影响，涉及神经内分泌调节、生殖行为以及在发育和衰老过程中的神经营养作用。该方法将包括识别对雌激素反应的信号转导级联，确定它们在体外增强神经肽/受体启动子-报告基因结构转录的能力，以及描述它们对雌激素受体激动剂和拮抗剂的敏感性。局部植入ER激动剂和拮抗剂，以及激活或抑制相关信号转导通路的药物。

Neuroendocrine neuropeptides such as vasopressin, oxytocin, and neurotensin serve as neurohormones, and neurotransmitters in the mammalian brain. The expression of the genes which encode these peptides, and their receptors, in brain neurons is regulated by steroid hormones such as estrogen, corticosteroids, and testosterone. This laboratory has for several years attempted to understand the importance of this hormonal modulation in the function of these neuropeptide systems, has used them to understand the cellular and molecular events which mediate the effects of steroids on neurotransmitter gene transcription in brain neurons. Data gathered in neuroblastoma cells, in primary neuronal cultures, and in the rat and mouse brain in vivo suggests that estrogen acts not only through the "classical" mechanism of action involving nuclear hormone receptor dimerization and binding to consensus hormone response elements, but also via "cross-talk" with other protein kinase-dependent signal transduction pathways such as protein kinase A, and the mitogen activated protein kinases. The studies proposed in this renewal application will test the hypothesis that estrogenic regulation of neuropeptide gene expression in vitro and in vivo. They will also investigate the relative roles of estrogen receptor-subtypes (ERalpha and the newly identified ERbeta) in these responses involves a mix of "classical" and protein kinase-dependent transcriptional actions. It is, thus, the combination of these effects which confer the dramatic effects of hormones such as estrogen on the brain involved in neuroendocrine regulation, reproductive behavior, as well as neurotropic effects in the developing and aging. The approach will involve identification of signal transduction cascades which respond to estrogen, determination of their ability to enhance transcription of neuropeptide/receptor promoter-reporter gene constructs in vitro, and profiling their sensitivity to estrogen receptor agonists and antagonists. Local implantation of ER agonists and antagonists, and pharmacologic agents which activate or inhibit the relevant signal transduction pathways will be used.