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缓慢输注升压血管紧张素 II (AngII) 后，可以观察到对高血压的易感性相当。下丘脑室旁核（PVN）对于整合和协调涉及心血管调节的神经体液反应至关重要。在高血压中，投射到脊髓的 PVN 神经元中 NMDA 受体的激活和 NADPH 氧化酶依赖性活性氧 (ROS) 的产生在增强动脉压升高的交感神经驱动方面发挥着关键作用。大量的 PVN 脊髓神经元含有雌激素受体 (ER)，这表明更年期激素的变化可以选择性地影响该群体的兴奋。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 氧化酶衍生的 ROS 的产生来改变兴奋性传递。这些变化最终可能导致更年期高血压的发生。因此，该提案将检验以下中心假设：更年期期间突触后 NMDA 受体和 ER¿ PVN 神经元内相关信号通路的变化使这些神经元倾向于增加应对高血压挑战的兴奋性。两个目标将检查更年期小鼠模型，以确定（1）更年期是否通过涉及 PVN 突触后 NMDA 受体的机制增加减缓升压性 AngII 高血压的易感性； (2) 含有 ERK 的 PVN 神经元中 NMDA 介导的反应是否表现出与高血压发展过程中兴奋性传递增强一致的适应性。这些研究将在完善的完整衰老模型和新的更年期 VCD 模型（包括一些 ER¿-GFP 转基因小鼠）中进行，并将使用缓慢的升压剂 AngII 输注作为高血压挑战。这些研究将使用多学科方法来完成，包括高分辨率电子显微镜免疫标记，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成分的亚细胞分布、NR1基因的时空缺失、定量RT-PCR、膜片钳记录、ROS成像和血压遥测测量。

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.