Disregulation of Potassium Channels in Menopausal Hot Flashes

描述(申请人提供)：潮热，一种突然的热感，是围绝经期和绝经后妇女最常见的医学症状。在外周，潮热的特征是血管扩张、心率加快和出汗。潮热的表达与绝经或卵巢切除手术开始时循环雌激素水平的降低有关。雌激素受体广泛分布于中枢神经系统和心血管系统。在中枢神经系统中，雌激素受体主要表达在下丘脑的视前区(POA)，这是与体温调节相关的温度敏感神经元的位置。人们认为潮热是由雌激素丢失引起的正常体温调节紊乱引起的，然而，其潜在的分子、细胞和生理机制尚不清楚。最近，通过生物信息学的应用，人们发现了一类新的离子通道，即背景漏钾通道或双孔结构域钾通道。在细胞和组织培养系统中，这些通道已被证明有助于建立细胞的静息膜电位。K2P通道的激活导致细胞超极化，从而抑制放电。虽然一些通道与温度敏感性、疼痛敏感性、对吸入麻醉剂的反应和神经保护有关，但这些通道中的大多数在活体中的生理功能尚未确定。本文假设雌激素调节中枢神经系统中K2P通道的表达，停用雌激素会导致这些通道的数量或活性减少。这种减少会使神经元去极化，导致更大的兴奋性和潮热的诱导。这项申请中提出的工作将使用功能性生物测定，即对雌激素缺乏和充足的小鼠尾部皮肤温度的无线电遥测监测，以监测在整个动物模型中激活和抑制K2P通道的药物的效果。免疫组织化学将被用来确定这些蛋白质是否在与雌激素受体相同的细胞中表达。这些通道的信使RNA的表达将使用实时荧光聚合酶链式反应和原位杂交进行定量。虽然这一应用将研究K2P通道在潮热发生中的作用，但增加我们对这些通道的生理功能的理解可能有助于深入了解与中枢神经系统过度兴奋相关的其他年龄相关疾病的机制。潮热是围绝经期和绝经期妇女最常见的医学症状。目前，缓解潮热症状最常用的治疗方法是激素替代疗法(HRT)。不幸的是，HRT与几个风险有关，包括激素依赖型癌症的增加，导致许多人寻求其他治疗。引起潮热的细胞和分子机制尚不清楚。本申请中提出的工作旨在调查导致潮热的潜在细胞和分子机制，从而开发安全有效的治疗方法。

DESCRIPTION (provided by applicant): The hot flash, an abrupt sensation of heat, is the most common medical complaint among peri- and post-menopausal women. Peripherally, hot flashes are characterized by vasodilation, increased heart rate, and perspiration. The expression of the hot flash is correlated with lowered levels of circulating estrogen at the onset of menopause or surgical removal of the ovaries. Estrogen receptors are widely distributed throughout the central nervous system and the cardiovascular system. Within the central nervous system estrogen receptors are prominently expressed in the preoptic area (POA) of the hypothalamus - the location of temperature sensitive neurons associated with thermoregulation. It is thought that hot flashes are caused by a disturbance of normal thermoregulation brought on by the loss of estrogen; however, the underlying molecular, cellular, and physiological mechanism is unknown. Recently, a new family of ion channels, the background leak potassium channels or two-pore domain potassium (K2P) channels has been identified through the use of bioinformatics. In cell and tissue culture systems these channels have been shown to contribute the establishment of the resting membrane potential of cells. Activation of K2P channels causes hyperpolarization of cells resulting in inhibition of firing. Although some of the channels have been associated with temperature sensitivity, sensitivity to pain, response to inhalant anesthetics, and neuroprotection, the physiological functions of most of these channels in living organisms have yet to be established. It is hypothesized herein that estrogen regulates the expression of K2P channels in the central nervous system and that the withdrawal of estrogen results in a decrease in the number or activity of these channels. This reduction would depolarize neurons leading to greater excitability and the induction of hot flashes. The work proposed in this application will use a functional bioassay, radiotelemetric monitoring of tail skin temperature from estrogen deficient and replete mice, to monitor the effects of drugs that activate and inhibit K2P channels in a whole animal model. Immunohistochemistry will be used to determine whether or not the proteins are expressed in the same cells as estrogen receptors. Expression of the messenger RNAs for the channels will be quantified using real time-PCR and in situ hybridization. Although this application will investigate the role of K2P channels in generating hot flashes, increasing our understanding of the physiological functions of these channels may provide insight into mechanisms of other age-associated diseases associated with hyperexcitability of the central nervous system. Hot flashes are the most common medical complaint among peri- and post-menopausal women. Currently, the most commonly used treatment to alleviate hot flash symptoms is hormone replacement therapy (HRT). Unfortunately, HRT is associated with several risks, including an increase in hormone dependent cancers, leading many to seek other treatments. The cellular and molecular mechanisms that cause hot flashes are unknown. The work proposed in this application is designed to investigate the underlying cellular and molecular mechanisms responsible for hot flashes, leading to the development of safe and effective treatments.