蓝斑-下丘脑去甲肾上腺素通路作用于热敏神经元引发围绝经期潮热的研究

The menopausal hot flash is closely related to the thermotaxic center dysfunction of the hypothalamic preoptic area, which is regulated by warm sensitive neurons. Our previous studies have shown that the norepinephrine pathway from locus coeruleus to hypothalamic preoptic area plays an important role in the occurrence of menopausal hot flash in the low estrogen status. However, it is not clear whether this pathway acts through warm sensitive neurons on hypothalamic preoptic area yet. Therefore, Trpm2-Cre and DBH-Cre mice are proposed to specifically mark warm-sensitive neurons on hypothalamic preoptic area and noradrenergic neurons in locus coeruleus respectively in our project, and we will explore the functional projection relationship between locus coeruleus and hypothalamic preoptic thermosensitive neurons, and study the expression and functional changes of the adrenergic receptor subtypes under a low estrogen level. We also conducted the specific chemogenetic manipulation for this neural pathway to observe the changes of the functional status of the warm sensitive neurons and peripheral body temperature. We try to elucidate the mechanism that norepinephrine pathway from the the locus coeruleus to hypothalamus preoptic area regulates the warm-sensitive neurons function, resulting in dysfunction of the thermotaxic center and changes of peripheral body temperature in the condition of low estrogen, eventually occurring the menopausal hot flash,which will establish a theoretical basis for establishment of the central nervous system theory of hot flash and the screening of neurotransmitter drug targets.

围绝经期潮热与下丘脑视前区体温调节中枢功能紊乱密切相关，而体温调节中枢功能主要是受热敏神经元调控。我们前期研究显示，低雌激素状态下，蓝斑-下丘脑视前区去甲肾上腺素通路在围绝经期潮热发生中起重要作用，但此通路是否通过作用于下丘脑视前区热敏神经元发挥作用尚不清楚，故本项目拟采用Trpm2-Cre和DBH-Cre小鼠分别特异性标记下丘脑视前区热敏神经元和蓝斑去甲肾上腺素能神经元，探讨低雌激素状态下，蓝斑和下丘脑视前区热敏神经元之间的功能投射关系，以及发挥作用的肾上腺素受体亚型的表达及功能变化，并对该神经通路进行特异性化学遗传操控研究，观察热敏神经元功能状态及外周体温的变化。阐明在低雌激素状态下，去甲肾上腺素经蓝斑-下丘脑视前区通路通过调节热敏神经元的功能活动，引起体温调节中枢功能异常，外周体温发生变化，最终引发围绝经期潮热的作用机制，为建立潮热发生的中枢理论和神经递质类药物靶点的筛选奠定理论基础

项目的背景：围绝经期潮热与下丘脑视前区体温调节中枢功能紊乱密切相关，而体温调节中枢功能主要受热敏神经元调控。我们前期研究显示，低雌激素状态下，蓝斑-下丘脑视前区去甲肾上腺素通路在围绝经期潮热发生机制中起重要作用，但此通路是否通过作用于下丘脑视前区热敏神经元发挥作用尚不清楚。主要研究内容：首先，通过观察不同环境温度刺激下大鼠去卵巢后体温调节功能是否出现异常，为潮热的研究奠定理论基础。其次，采用Trpm2-Cre小鼠特异性激活或抑制Trpm2神经元观察小鼠的体温变化。通过RNA-scope特异性标记TRPM2阳性神经元中谷氨酸能和GABA能神经元类型及激活或抑制Trpm2阳性神经元后谷氨酸能和GABA的表达变化，探讨TRPM2热敏神经元中谷氨酸能和GABA能神经元类型和功能的变化参与围绝经期潮热的可能机制。最后，通过观察TRPV1与α2-ADR的共标及低雌激素状态下的表达变化探讨发挥作用的肾上腺素受体亚型。重要结果：一、在不同的环境温度刺激下，去卵巢大鼠背部、尾部和爪垫体表温度的异常变化较为显著，故我们推测去卵巢大鼠发生了类似于人体潮热的症状。二、去卵巢小鼠POA区（下丘脑视前区）TRPM2热敏神经元的功能及谷氨酸能和GABA能神经元表达异常可能导致体温调控发生障碍，在围绝经期潮热的发生过程中可能发挥关键作用。三、POA内TRPV1与α2-ADR共表达，大鼠去卵巢后二者的表达量发生改变，提示TRPV1的表达可能受α2肾上腺素能受体的调节。关键数据及其科学意义：特异性抑制TRPM2热敏神经元，SHAM组散热反应被抑制，体温上升，而OVX组体温无明显波动，这表明去卵巢小鼠POA区TRPM2热敏神经元的功能异常导致体温调控发生障碍。特异性激活或抑制TRPM2热敏神经元，OVX组TRPM2热敏神经元中谷氨酸和GABA的合成、转化和分泌等过程发生改变，导致谷氨酸能和GABA能神经元比率的异常。POA内TRPV1表达增加，NE含量和α2-ADR表达减少。上述表变化阐明了在低雌激素状态下，去甲肾上腺素通路通过调节热敏神经元的功能活动引发围绝经期潮热，为建立潮热发生的中枢理论和神经递质类药物靶点的筛选奠定理论基础。