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温度通过瞬时受体电位离子通道调节室旁核的交感节前神经元。

Temperature modulates PVN pre-sympathetic neurones via transient receptor potential ion channels.

作者信息

O'Brien Fiona, Feetham Claire H, Staunton Caroline A, Hext Kathryn, Barrett-Jolley Richard

机构信息

Department of Musculoskeletal Ageing Science, Faculty of Health and Life Sciences, University of Liverpool, Liverpool, United Kingdom.

出版信息

Front Pharmacol. 2023 Oct 18;14:1256924. doi: 10.3389/fphar.2023.1256924. eCollection 2023.

Abstract

The paraventricular nucleus (PVN) of the hypothalamus plays a vital role in maintaining homeostasis and modulates cardiovascular function via autonomic pre-sympathetic neurones. We have previously shown that coupling between transient receptor potential cation channel subfamily V Member 4 (Trpv4) and small-conductance calcium-activated potassium channels (SK) in the PVN facilitate osmosensing, but since TRP channels are also thermosensitive, in this report we investigated the temperature sensitivity of these neurones. TRP channel mRNA was quantified from mouse PVN with RT-PCR and thermosensitivity of Trpv4-like PVN neuronal ion channels characterised with cell-attached patch-clamp electrophysiology. Following recovery of temperature-sensitive single-channel kinetic schema, we constructed a predictive stochastic mathematical model of these neurones and validated this with electrophysiological recordings of action current frequency. 7 thermosensitive TRP channel genes were found in PVN punches. Trpv4 was the most abundant of these and was identified at the single channel level on PVN neurones. We investigated the thermosensitivity of these Trpv4-like channels; open probability (Po) markedly decreased when temperature was decreased, mediated by a decrease in mean open dwell times. Our neuronal model predicted that PVN spontaneous action current frequency (ACf) would increase as temperature is decreased and in our electrophysiological experiments, we found that ACf from PVN neurones was significantly higher at lower temperatures. The broad-spectrum channel blocker gadolinium (100 µM), was used to block the warm-activated, Ca-permeable Trpv4 channels. In the presence of gadolinium (100 µM), the temperature effect was largely retained. Using econazole (10 µM), a blocker of Trpm2, we found there were significant increases in overall ACf and the temperature effect was inhibited. Trpv4, the abundantly transcribed thermosensitive TRP channel gene in the PVN appears to contribute to intrinsic thermosensitive properties of PVN neurones. At physiological temperatures (37°C), we observed relatively low ACf primarily due to the activity of Trpm2 channels, whereas at room temperature, where most of the previous characterisation of PVN neuronal activity has been performed, ACf is much higher, and appears to be predominately due to reduced Trpv4 activity. This work gives insight into the fundamental mechanisms by which the body decodes temperature signals and maintains homeostasis.

摘要

下丘脑室旁核(PVN)在维持体内平衡中起着至关重要的作用,并通过自主神经节前交感神经元调节心血管功能。我们之前已经表明,PVN中瞬时受体电位阳离子通道亚家族V成员4(Trpv4)与小电导钙激活钾通道(SK)之间的偶联促进了渗透压感知,但由于TRP通道也对温度敏感,在本报告中我们研究了这些神经元的温度敏感性。用逆转录聚合酶链反应(RT-PCR)从小鼠PVN中定量TRP通道mRNA,并用细胞贴附式膜片钳电生理学方法表征Trpv4样PVN神经元离子通道的温度敏感性。在恢复温度敏感单通道动力学模式后,我们构建了这些神经元的预测性随机数学模型,并用动作电流频率的电生理记录对其进行了验证。在PVN组织块中发现了7个温度敏感的TRP通道基因。其中Trpv4最为丰富,并在PVN神经元的单通道水平上得到鉴定。我们研究了这些Trpv4样通道的温度敏感性;当温度降低时,开放概率(Po)显著降低,这是由平均开放驻留时间的减少介导的。我们的神经元模型预测,随着温度降低,PVN自发动作电流频率(ACf)会增加,并且在我们的电生理实验中,我们发现较低温度下PVN神经元的ACf显著更高。使用广谱通道阻滞剂钆(100 μM)来阻断温暖激活的、钙通透的Trpv4通道。在存在钆(100 μM)的情况下,温度效应在很大程度上得以保留。使用Trpm2的阻滞剂酮康唑(10 μM),我们发现总体ACf显著增加,并且温度效应受到抑制。PVN中大量转录的温度敏感TRP通道基因Trpv4似乎对PVN神经元的内在温度敏感特性有贡献。在生理温度(37°C)下,我们观察到ACf相对较低,主要是由于Trpm2通道的活性,而在室温下,之前对PVN神经元活动的大多数表征都是在此温度下进行的,ACf要高得多,并且似乎主要是由于Trpv4活性降低。这项工作深入了解了身体解码温度信号并维持体内平衡的基本机制。

https://cdn.ncbi.nlm.nih.gov/pmc/blobs/2825/10618372/5cf20e4c16b5/fphar-14-1256924-g002.jpg

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