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大脑中充当神经激素和神经递质。在脑神经元中，编码这些肽及其受体的基因的表达受到类固醇激素如雌激素、皮质类固醇和睾酮的调节。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，并利用它们来了解介导类固醇对脑神经元中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，在原代神经元培养，并在大鼠和小鼠的大脑在体内收集的数据表明，雌激素不仅通过“经典”的作用机制，涉及核激素受体二聚化和结合的共识激素反应元件，但也通过“串扰”与其他蛋白激酶依赖的信号转导途径，如蛋白激酶A，和丝裂原活化蛋白激酶。本更新申请中提出的研究将检验雌激素在体外和体内调节神经肽基因表达的假设。他们还将研究雌激素受体亚型（ER α和新发现的ER β）在这些反应中的相对作用，这些反应涉及“经典”和蛋白激酶依赖性转录作用的混合。 因此，正是这些作用的组合赋予激素如雌激素对参与神经内分泌调节、生殖行为以及发育和衰老中的亲神经作用的大脑的显著作用。该方法将涉及识别响应雌激素的信号转导级联，确定它们在体外增强神经肽/受体启动子-报告基因构建体转录的能力，并分析它们对雌激素受体激动剂和拮抗剂的敏感性。 将使用ER激动剂和拮抗剂以及激活或抑制相关信号转导途径的药理学药物的局部植入。

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.