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Activation of metabotropic glutamate receptor 1 inhibits chronic intermittent hypoxia-induced carotid body plasticity in rats

LI Chao-Hong^1,2, ZHAO Chen-Lu¹, LIU Yu-Zhen^1,*

¹The First Affiliated Hospital of Xinxiang Medical University, Henan Key Laboratory of Neural Regeneration and Repairment, Life Sciences Research Center, Weihui 453100, China；²Department of Cardiology, The Second Affiliated Hospital of Chongqing Medical University, Chongqing 404100, China

Abstract

The purpose of the present study was to explore the role of carotid body metabotropic glutamate receptor 1 (mGluR1) in chronic intermittent hypoxia (CIH)-induced carotid body plasticity. Sprague Dawley (SD) rats were exposed to CIH (6%–21% O2, 4 min/cycle, 8 h/day) for 4 weeks. The blood pressure of rats was monitored non-invasively by tail-cuff method under consciousness. RT-qPCR was used to examine the mRNA expression level of mGluR1 in rat carotid body. Western blot was used to detect the protein expression level of mGluR1 in rat carotid body. The role of mGluR1 in CIH-induced carotid body sensory long-term facilitation (sLTF) was investigated by ex vivo carotid sinus nerve discharge recording, and the carotid body sLTF was evoked by a 10-episode of repetitive acute intermittent hypoxia (AIH: 1 min of 5% O2 interspersed with 5 min of 95% O2). The results showed that: 1) CIH increased the systolic blood pressure (P < 0.001), diastolic blood pressure (P < 0.005) and mean arterial blood pressure (P < 0.001) of rats; 2) CIH decreased the mRNA and protein levels of mGluR1 in the rat carotid body (P < 0.01); 3) 4 weeks of CIH induced carotid body sLTF significantly, exhibiting as an increasing baseline sensory activity during post-AIH, which was inhibited by application of an agonist of group I metabotropic glutamate receptors, (S)-3,5-dihydroxyphenylglycine (DHPG), during sLTF induction (P < 0.005). In summary, these results suggest that activation of mGluR1 inhibits CIH-induced carotid body plasticity in rats.

Key words: metabotropic glutamate receptor 1; chronic intermittent hypoxia;

Received: 　　Accepted:

Corresponding author: 刘玉珍　　E-mail: yuzhenliu@xxmu.edu.cn

DOI: 10.13294/j.aps.2023.0062

Citing This Article：

LI Chao-Hong, ZHAO Chen-Lu, LIU Yu-Zhen. Activation of metabotropic glutamate receptor 1 inhibits chronic intermittent hypoxia-induced carotid body plasticity in rats. Acta Physiol Sin 2023; 75 (5): 629-635 (in Chinese with English abstract).