Li Chaohong, Zhao Baosheng, Zhao Chenlu, Huang Lu, Liu Yuzhen
Henan Key Laboratory of Neural Regeneration and Repairment, Life Science Research Center, The First Affiliated Hospital of Xinxiang Medical University, Weihui, China.
Department of Thoracic Surgery, The First Affiliated Hospital of Xinxiang Medical University, Weihui, China.
Front Neurosci. 2021 Oct 5;15:741214. doi: 10.3389/fnins.2021.741214. eCollection 2021.
The carotid body (CB) plays a critical role in oxygen sensing; however, the role of glutamatergic signaling in the CB response to hypoxia remains uncertain. We previously found that functional multiple glutamate transporters and inotropic glutamate receptors (iGluRs) are expressed in the CB. The aim of this present research is to investigate the expression of group I metabotropic glutamate receptors (mGluRs) (mGluR1 and 5) in the CB and its physiological function in rat CB response to acute hypoxia. RT-PCR and immunostaining were conducted to examine the mRNA and protein expression of group I mGluRs in the human and rat CB. Immunofluorescence staining was performed to examine the cellular localization of mGluR1 in the rat CB. carotid sinus nerve (CSN) discharge recording was performed to detect the physiological function of mGluR1 in CB response to acute hypoxia. We found that (1) mRNAs of mGluR1 and 5 were both expressed in the human and rat CB. (2) mGluR1 protein rather than mGluR5 protein was present in rat CB. (3) mGluR1 was distributed in type I cells of rat CB. (4) Activation of mGluR1 inhibited the hypoxia-induced enhancement of CSN activity (CSNA), as well as prolonged the latency time of CB response to hypoxia. (5) The inhibitory effect of mGluR1 activation on rat CB response to hypoxia could be blocked by GABA receptor antagonist. Our findings reveal that mGluR1 in CB plays a presynaptic feedback inhibition on rat CB response to hypoxia.
颈动脉体（CB）在氧感知中起关键作用；然而，谷氨酸能信号在CB对缺氧反应中的作用仍不确定。我们先前发现功能性多种谷氨酸转运体和离子型谷氨酸受体（iGluRs）在CB中表达。本研究的目的是研究I组代谢型谷氨酸受体（mGluRs）（mGluR1和5）在CB中的表达及其在大鼠CB对急性缺氧反应中的生理功能。进行逆转录聚合酶链反应（RT-PCR）和免疫染色以检测人和大鼠CB中I组mGluRs的mRNA和蛋白表达。进行免疫荧光染色以检测大鼠CB中mGluR1的细胞定位。进行颈动脉窦神经（CSN）放电记录以检测mGluR1在CB对急性缺氧反应中的生理功能。我们发现：（1）mGluR1和5的mRNA在人和大鼠CB中均有表达。（2）大鼠CB中存在mGluR1蛋白而非mGluR5蛋白。（3）mGluR1分布于大鼠CB的I型细胞中。（4）mGluR1的激活抑制了缺氧诱导的CSN活性增强（CSNA），并延长了CB对缺氧反应的潜伏期。（5）mGluR1激活对大鼠CB对缺氧反应的抑制作用可被GABA受体拮抗剂阻断。我们的研究结果表明，CB中的mGluR1对大鼠CB对缺氧的反应起突触前反馈抑制作用。
