应激条件下终纹床核GABA能神经环路对下丘脑室旁核CRH神经元的输出机制

The bed nucleus of stria terminalis(BNST) is the direct relay nucleus connection the prefrontal cortex and hippocampus with paraventricular nucleus (PVN),which has critical role in stress-induced affection and memory dysfunction.PVN is richly inervated by GABAergic projections from the bed nucleus of stia terminalis. The stress-induced changes of glucocorticoids and its receptor are the main factors on HPA axis dysfunction，but the detailed neuronal modulation mechanism remain to be elucidated. Due to the strong expression of glucocoticoids receptor mRNA and immunoreactivity in the bed nucleus of stria terminalis, we propose that the GABAergic neuronal function is down-regulated by excess glucocorticoid through glucocorticoid receptor in BNST, thus the inhibitory projection of BNST on PVN is removed, resulting the over-activation of CRH neuron in PVN.This study will use vGAT-ChR2-EYFP transgenic mice, in which the light-sensitive channel (channelrhodposin) specifictly expressed in GABAergic neurons and blue lase-light will induce GABA release from those neuron,combined with immonohistochemistry, molecular biology and micro-electrodes array recording technology, to study the role of GABAergic neuron of BNST in stress-induced HPA axis activation. First we will study the effects of stress on the GABAergic neuronal morphology and function in BNST,and answer the question if the stress impair the synthesis and transport of the GABA neurotransmitter and the electrophysiological activity of GABAergic neuron in BSNT.Then we will explore the stress-induced changes of GABAergic circuit in BNST by using MEA and electrophysiological recording, we will answer the question if the stress impair the synaptic transmission and synaptic integration in BNST. Finally the mechanism of stress-induced BNST synaptic output to PVN will be studied in depressed animal mode.Thus,we expect to clarify the role and the mechnism of GABAergic neuron of BNST in stress-induced HPA axis activation.

终纹床核是前额叶、海马传入下丘脑室旁核（PVN）最直接的中继核团，在应激引起的情感和记忆环路中具有重要作用，其对PVN的支配主要是GABA能神经元投射。应激所引起的糖皮质激素升高及其受体（GR）的变化是HPA轴激活的最主要因素，但其具体的神经调节机制尚不明确。终纹床核内表达大量的糖皮质激素受体免疫阳性神经元，因此我们提出：过量糖皮质激素通过糖皮质激素受体下调终纹床核内GABA能神经元的功能，从而解除终纹床核对PVN的抑制作用，导致PVN中CRH神经元过度驱动。本课题拟利用光敏感通道特异性表达在GABA能神经元的转基因小鼠，结合免疫组化、分子生物学和微电极阵列记录技术，研究应激对终纹床核GABA能神经元的形态和功能的影响，揭示应激状态下终纹床核内GABA能神经微环路的改变机制，探讨终纹床核在应激条件下对PVN的输出调节机制。期望能阐述终纹床核GABA神经环路在应激致抑郁产生中的作用和机制。

项目拟检测终纹床核（BNST）在抑郁发生发展过程中的作用，特别是抑郁过程中终纹床核GABA能神经环路的作用和机制。采用光遗传学，行为学，电生理学和形态学等方法，探讨了终纹床核的神经元投射及其功能和机制。1、树鼩作为最接近灵长类的物种，常常被用来作为慢性应激的模型。通过在终纹床核注射荧光金，我们对支配树鼩终纹床核的神经元进行了全脑标记。研究发现前额叶皮层，内嗅皮层，腹侧下托，杏仁核，腹侧被盖区，臂旁核对终纹床核有大量投射（neuroscience,2016）。2、采用vGat小鼠激活终纹床核GABA能神经元抑郁相关行为学研究：通过强迫游泳、悬尾实验，发现BNST的GABA能神经元激活可显著增加抑郁样症状，但血浆皮质酮水平没有明显区别，也不产生明显的焦虑症状。3、发现光激活终纹床核GABA能神经元可降低雄性性相关行为，在理毛行为、睡眠以及吃食物过程中BNST中的GABA能具有特定的作用。4、通过慢性不可预测性应激、脑室内注射视黄酸（RA）以及慢性束缚三种方式造抑郁模型，比较了行为学，突触可塑性和受体表达的差异。5、通过光激活下丘脑室旁核中的CRH神经元，通过钻管测试发现PVN中CRH神经元特异性激活可明显转变动物的社会等级，在侧脑室注射CRH同样可以导致社会等级的变化。