权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

A cellular mechanism for the release of glutamate as a neural signal in hypothalamic peptidergic neurons

下丘脑肽能神经元释放谷氨酸作为神经信号的细胞机制

基本信息

批准号：
14580721
负责人：
HISANO Setsuji
金额：
$ 2.3万
依托单位：
University of Tsukuba
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2003
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-14580721/
关键词：
Hypothalamus Glutamate Transporter Neuroendocrine neuron Stress 体液調節

项目摘要

To clarify a functional role of endogenous glutamate in hypothalamic peptidergic neurons, the present study analyzed phenotypes of neurons which express a vesicular glutamate transporter (VGLUT2), the ultrastructural localization of VGLUT2 in neurohypophysial terminals and changes of VGLUT2 gene expression in the paraventricular (PVN) and supraoptic (SON) nuclei by stressful stimuli. In situ hybridization combined with immunohistochemistry revealed VGLUT2 gene expression in neurons containing vasopressin, oxytocin, orexin or proopiomelanocortin of the rat hypothalamus, suggesting the presence of neurotransmitter glutamate in these peptidergic neurons. Double-label immunofluorescence staining demonstrated VGLUT2-staining in vasopressin-containing terminals of the rat neurohypophysis but this was unable to observe ultrastructurally because of the high background caused by the anti-VGLUT2 antiserum used. Quantitative in situ hybridization analysis with BAS5000 and NIH image demonstrated that gene expression of corticotropin-releasing hormone but not VGLUT2 was significantly upregulated in the PVN of mice exposed to restraint stress. In experiments of osmotic challenges in rats, VGLUT2 gene expression was upregulated throughout the PVN and SON of water-deprivation animals, whereas the expression in salt-loading (drinking of 2% NaCl) animals was upregulated only in particular subregions of these nuclei where vasopressin neurons are predominantly located. These changes in VGLUT2 gene expression induced by osmotic stimulations were statistically significant as compared with the expression level in the control animal (euhydrated rats). These results show the regulation of VGLUT2 expression at the transcription level, dependent on the status of hormonal secretion from the neurohypophysis, and suggest autocrine or paracrine modulation by endogenous glutamate for the peptide release in some, but not all, peptidergic neurons of the hypothalamus.

为了阐明内源性谷氨酸在下丘脑肽能神经元中的功能作用，本研究分析了表达谷氨酸囊泡转运体（VGLUT2）的神经元的表型、VGLUT2在神经垂体末梢的超微结构定位以及VGLUT2基因在室旁核（PVN）和视上核（SON）中的表达在应激刺激下的变化。原位杂交结合免疫组织化学发现，VGLUT2基因在大鼠下丘脑含有抗利尿激素、催产素、食欲素或促黑素原的神经元中表达，提示这些肽能神经元中存在神经递质谷氨酸。双标记免疫荧光染色显示，大鼠神经垂体含有抗利尿激素的末端有vglut2染色，但由于抗vglut2抗血清的高背景，无法在超微结构上观察到。基于BAS5000和NIH图像的定量原位杂交分析表明，抑制应激小鼠PVN中促肾上腺皮质激素释放激素基因表达显著上调，而VGLUT2基因表达不上调。在大鼠渗透挑战实验中，VGLUT2基因表达在缺水动物的整个PVN和SON中上调，而在盐负荷（饮用2% NaCl）动物中，VGLUT2基因表达仅在这些核的特定亚区上调，这些亚区主要位于加压素神经元。与对照组（脱水大鼠）相比，渗透刺激诱导的VGLUT2基因表达变化具有统计学意义。这些结果表明VGLUT2在转录水平上的表达调控依赖于神经垂体激素分泌的状态，并提示内源性谷氨酸调节下丘脑部分（但不是全部）肽能神经元的自分泌或旁分泌肽释放。