围绝经期蓝斑去甲肾上腺素通路异常的分子生物学机制

Hot flashes is common perimenopausal symptoms and closely related to the central thermoregulatory dysfunction in the preoptic area of hypothalamus. Norepinephrine is known to be involved in the thermoregulation process. Our previous work showed that the expressions of estrogen receptors and norepinephrine in the locus coeruleus, and the density of norepinephrine fibers and alpha 1 adrenaline receptor in the preoptic area of hypothalamus were all decreased in the ovariectomized rats. Hence, this project intends to research the molecular biology mechanism of abnormal locus coeruleus norepinephrine pathways caused by estrogen receptors and signal pathway under low estrogen levels during menopausal transition. First of all, in the locus coeruleus area: to determine the projection corresponding connections between locus coeruleus subregions and different nuclei in the preoptic area of hypothalamus and the expressions of estrogen receptor subtypes and signal pathway in locus coeruleus subregions. The changes of norepinephrine pathway and body temperature of the rats are detected after the adminstration of estrogen agonists and antagonists and the damage of locus coeruleus subregions, respectively. Second, in the preoptic area of hypothalamus: the changes of norepinephrine in the synaptic cleft of different nuclei are tested by real-time micro dialysis combined with carbon fiber electrode electrochemical technology. The relationships between estrogen receptors and norepinephrine transporter or degradation enzymes are observed in the presynaptic membrane of norepinephrine axon endings in different groups. This project will illuminate the mechanism of estrogen receptors reducing the norepinephrine through norepinephrine synthesis, absorption and degradation, and of the neurotransmitter adjusting body temperature, which lays a foundation for the central theory of hot flashes.

围绝经期常见症状潮热与下丘脑视前区体温调节功能紊乱密切相关，去甲肾上腺素可能参与此体温调节过程。我们前期工作显示去卵巢大鼠雌激素受体在蓝斑表达降低,蓝斑表达去甲肾上腺素神经元数量减少及向下丘脑视前区投射的神经纤维密度降低，下丘脑视前区肾上腺素α1受体减少。故本项目拟研究围绝经期低雌激素状态下，雌激素受体及信号通路的改变可能致蓝斑去甲肾上腺素通路异常的分子生物学机制。首先，在蓝斑部位：确定蓝斑与下丘脑视前区不同核团的投射对应关系和雌激素受体亚型的表达分布及信号通路的变化情况。使用雌激素受体激动剂、拮抗剂及损毁蓝斑观察去甲肾上腺素通路及体温的变化。其次，在下丘脑视前区：微透析结合碳纤维电极电化学技术检测不同核团突触间隙去甲肾上腺素浓度，观察去甲肾上腺素纤维突触前膜雌激素受体与去甲肾上腺素转运体和降解酶的关系。将阐明雌激素受体致去甲肾上腺素降低的原因（合成、重吸收和降解）及通过神经递质调控体温的机制，为建立潮热中枢理论奠定基础

围绝经期是妇女生育功能从旺盛走向衰退的过渡时期，约 50%-75%的妇女会出现一系列程度不同的症状，其中 约 2/3 的围绝经期妇女出现潮热症状。潮热与心血管疾病的发生密切相关，并将潮热视为心血管疾病发生早期的“ 警示灯”。此外，心悸，肥胖、口干和心脑血管疾病等也是围绝经期综合征的常见症状。它们都严重影响围绝经期妇女的生活质量。本课题从中枢和外周两方面对潮热的发病机制进行研究，同时也对肥胖和口干的病因进行了探讨。其结果如下：1. 低雌激素状态下蓝斑 NE 合成减少，重吸收和降解增强。其综合结果导致下丘脑视前区 NE 减少。我们猜测以上变化最终导致体温调节中枢温度敏感神经元功能障碍而出现潮热的症状。2. 低雌激素状态下血浆肾上腺素含量升高，去甲肾上腺素、间羟去甲肾上腺素含量降低，心脏舒张功能减退，外周血管舒缩功能障碍， 动脉血压升高。蛋白质相互作用分析显示 GLUT4 为重要的节点蛋白质。这可能是更年期女性出现潮热的外周原因之一，并可导致高血压、冠心病等症状的发生。3. 低雌激素可导致肝细胞脂质代谢发生障碍，血清内甘油三酯含量增加，肝细胞胞浆内脂滴数量增多，透射电镜显示肝脏细胞内出现肥大畸形的线粒体。下颌下腺细胞出现线粒体、内质网等亚细胞结构的改变，引起细胞萎缩、凋亡。腺泡和导管排列疏松，部分细胞出现细胞膜向细胞浆凹陷的现象。以上改变可解释更年期女性为什么会出现肥胖和口干的症状。本研究为围绝经期出现的多种症状由其是潮热的发病机制奠定了理论与实践基础。在潮热研究方面挖掘出差异表达蛋白质可作为围绝经期症状和疾病诊断生物标志物和治疗靶点，为制定更为有效且安全的临床围绝经期个体化精准医疗提供理论依据。