MENOPAUSAL CHANGES IN HYPOTHALAMUS AND HYPERTENSION SUSCEPTIBILITY

描述（由申请人提供）：绝经后，女性高血压和心血管风险增加。我们的初步数据表明，在绝经期小鼠模型中，可以观察到缓慢加压血管紧张素II （AngII）输注后对高血压的易感性。下丘脑室旁核（PVN）是整合和协调参与心血管调节的神经体液反应的关键。在高血压中，投射到脊髓的PVN神经元中NMDA受体激活和NADPH氧化酶依赖的活性氧（ROS）的产生在增强交感驱动中起关键作用，这是动脉压升高的基础。大量pvn -脊髓神经元含有雌激素受体（ER）¿，这表明更年期激素的改变可能选择性地影响这一人群的兴奋。特别是，性腺类固醇可以通过调节NMDA受体的表达和/或亚细胞分布、电压门控Ca2+通道电流和/或NADPH氧化酶衍生ROS的产生来改变兴奋性传递。这些变化最终可能导致绝经期高血压的发生。因此，本研究将验证一个中心假设，即绝经期间内耳PVN神经元突触后NMDA受体和相关信号通路的变化，使这些神经元在应对高血压挑战时容易增加兴奋性。研究绝经小鼠模型有两个目的：(1)绝经是否通过与PVN突触后NMDA受体相关的机制增加对慢压性AngII高血压的易感性；(2)在高血压发生过程中，含有ER的PVN神经元中nmda介导的反应是否表现出与兴奋性传递增强相一致的适应性。这些研究将在成熟的完整衰老模型和包括ER¿- gfp转基因小鼠在内的更年期新VCD模型中进行，并将使用缓慢的降压药AngII-输注作为高血压挑战。这些研究将使用多学科方法来实现，包括高分辨率电镜免疫标记，以确定ER¿-GFP标记的PVN神经元中必需的NMDA NR1受体和相关信号通路组分的亚细胞分布，NR1基因的时空缺失，定量RT-PCR，膜片钳记录，ROS成像和遥测血压。

DESCRIPTION (provided by applicant): After menopause, hypertension and cardiovascular risk increases in women. Our preliminary data indicate that a comparable susceptibility to hypertension can be observed following slow pressor angiotensin II (AngII) infusion in a menopausal mouse model. The hypothalamic paraventricular nucleus (PVN) is critical for integrating and coordinating neurohumoral responses involved in cardiovascular regulation. In hypertension, NMDA receptor activation and NADPH oxidase-dependent reactive oxygen species (ROS) production in PVN neurons that project to the spinal cord plays a pivotal role in enhancing the sympathetic drive that underlies the elevation of arterial pressure. A significant number of PVN-spinal neurons contain the estrogen receptor (ER) ¿, suggesting that hormone alterations in menopause could selectively influence excitation in this population. In particular, gonadal steroids could alter excitatory transmission by regulating the expression and/or subcellular distribution of the NMDA receptor, voltage-gated Ca2+ channel currents and/or the generation of NADPH oxidase derived ROS. Such changes could ultimately contribute to the development of hypertension observed in menopause. Therefore, this proposal will test the central hypothesis that changes in postsynaptic NMDA receptors and associated signaling pathways within ER¿ PVN neurons during menopause predisposes these neurons to increase excitability in response to hypertensive challenges. Two aims will examine mouse models of menopause to determine (1) whether menopause increases the susceptibility to slow pressor AngII hypertension through mechanisms involving post-synaptic NMDA receptors in the PVN; and (2) if NMDA-mediated responses in ER¿-containing PVN neurons show adaptations consistent with the potentiation of excitatory transmission during the development of hypertension. These studies will be conducted in the well-established intact aging model and the new VCD model of menopause including some ER¿-GFP transgenic mice, and will use slow pressor AngII- infusion as the hypertensive challenge. These studies will be achieved using a multidisciplinary approach including high resolution electron microscopic immunolabeling to identify the subcellular distribution of essential NMDA NR1 receptors and related signaling pathway components in ER¿-GFP labeled PVN neurons, spatial-temporal deletion of the NR1 gene, quantitative RT-PCR, patch-clamp recording, ROS imaging, and telemetric measurement of blood pressure.