ERα-initiated signals in the medial amygdala prevent stress-induced hypertension

描述（由申请人提供）：这是一份Ruth L. Kirschstein NRSA促进健康相关研究多样性个人博士前奖学金（家长F31-多样性）奖的申请，申请人是贝勒医学院的研究生Antentor Othrell Hinton， Jr.。高血压（HTN）是全球心血管疾病的主要原因，也是女性的头号杀手。目前迫切需要治疗和预防HTN的干预措施。心理压力有助于人类HTN的发展，而这些影响至少部分是由杏仁核中的神经元介导的。在人类、小鼠和大鼠中，应激时内侧杏仁核（MeA）的神经活动与血压水平（BP）呈正相关，雌激素通过雌激素受体-α (ERα)减弱应激诱导的内侧杏仁核中c-fos的表达，但其机制尚不清楚。雌激素替代疗法（ERT）可以降低绝经后妇女的血压，但也会增加中风和血栓栓塞的风险。这一建议的前提是，了解雌激素抗高血压作用的具体途径可能会导致HTN的新颖和更安全的治疗方法。在这里，我们假设在MeA神经元中er α启动的信号通路阻止应激诱导的HTN。在Aim 1中，我们假设MeA中的ERα介导雌激素作用以防止应激诱导的HTN。我们制备了SIM1 -ERα- ko小鼠，其中ERα主要在MeA SIM1神经元中缺失。虽然雌激素替代可以防止野生型卵巢切除（OVX）雌性应激诱导的HTN，但这些作用在sim1-ERα-KO小鼠中被减弱。为了证实这些发现，我们将以立体定向方式将AAV-Cre（对照AAV-GFP）注射到lox-ERα雌性小鼠的MeA中。在Aim2中，我们发现雌性小鼠中央给药选择性ERα激动剂丙基吡唑三醇（PPT）增加了ERα和p85a（一种PI3K调节亚基）的相互作用，并增加了杏仁核中AKT的磷酸化（PI3K介导的事件）。这使我们假设MeA中的PI3K介导雌激素作用以防止应激诱导的HTN。为了证实这些发现，我们将立体定向注射AAV-Cre（对照AAV-GFP）到lox-p110a雌性小鼠的MeA中。在Aim 3中，初步数据表明，通过硝酸盐/亚硝酸盐测定，中央给药PPT刺激杏仁核中一氧化氮（NO）的产生。我们将测试ERα i nNOS神经元（nNOS-ERα- ko小鼠）的缺失是否会减弱应激时E2的降压作用，并使用NO供体拯救sim1-ERα-KO雌性小鼠。这一建议将告诉我们雌激素/ERα和MeA调控在应激诱导HTN中的作用。我们的研究将证明选择性激活MeA ERα可以降低血压的概念，从而可能确定治疗HTN的新药物靶点。

DESCRIPTION (provided by applicant): This is an application for a Ruth L. Kirschstein NRSA for Individual Predoctoral Fellowship to Promote Diversity in Health-Related Research (Parent F31- Diversity) award for Antentor Othrell Hinton, Jr., a graduate student at Baylor College of Medicine. Hypertension (HTN) is the leading cause of cardiovascular disease worldwide and the number one killer in women. Interventions that treat and prevent HTN are urgently needed. Psychological stress contributes to development of HTN in humans, and these effects are mediated at least partly by neurons in the amygdala. In humans, mice and rats, neural activities in the medial amygdala (MeA) are positively associated with levels of blood pressure (BP) during stress and estrogens attenuate stress-induced c-fos expression in the MeA via estrogen receptor-α (ERα), yet the mechanisms remain unknown. Estrogen replacement therapy (ERT) lowers BP in postmenopausal women, but it also increases the risk of stroke and thromboembolism. It is the premise of this proposal that understanding specific pathways underlying the anti-hypertensive effects of estrogens may lead to novel and safer therapies for HTN. Here we hypothesize that ERα-initiated signaling pathways in MeA neurons prevent stress-induced HTN. In Aim 1, we hypothesized that ERα in the MeA mediates estrogenic effects to prevent stress-induced HTN. We generated sim1-ERα-KO mice, in which ERα is deleted mostly from MeA SIM1 neurons. Although estrogen replacement prevented stress-induced HTN in wild type ovariectomized (OVX) females, these effects were blunted in sim1-ERα-KO mice. To confirm these findings we will stereotaxically inject AAV-Cre (vs. AAV-GFP as a control) into the MeA of lox-ERα female mice. In Aim2, we found that central administration of a selective ERα agonist, propyl pyrazole triol (PPT), in female mice increased interactions of ERα and p85a (a regulatory PI3K subunit), and increased phosphorylation of AKT (a PI3K-mediated event) in the amygdala. This led us to hypothesize that PI3K in the MeA mediates estrogenic effects to prevent stress-induced HTN. To confirm these findings, we will stereotaxically inject AAV-Cre (vs. AAV-GFP as a control) into the MeA of lox-p110a female mice. In Aim 3, preliminary data suggest that central administration of PPT stimulates nitric oxide (NO) production in the amygdala via nitrate/nitrite assay. We will test if deletion of ERα i nNOS neurons (nNOS-ERα-KO mice) will blunt anti-hypertensive effects of E2 during stress and, rescue sim1-ERα-KO female mice using a NO donor. This proposal will teach us about the role of estrogens/ERα and MeA regulation in stress-induced HTN. Our studies will prove the concept that selective activation of MeA ERα can decrease BP, and therefore may identify a novel drug target for the treatment of HTN.