Glutamate metabotropic receptors in the lateral hypothalamus/perifornical area reduce the CO2 chemoreflex

•Glutamate acting on metabotropic receptors in the LH/PFA inhibits CO2 drive to breath.•The tonic inhibition provided by glutamate in the LH/PFA occurs in wakefulness.•Glutamate metabotropic signaling in LH/PFA does not affect normocapnic breathing. It has been shown that the lateral hypothalamus/pe...

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Bibliographic Details
Published in:Respiratory physiology & neurobiology 2019-02, Vol.260, p.122-130
Main Authors: Rodrigues, Laísa Taís Cabral, da Silva, Eliandra Nunes, Horta-Júnior, José de Anchieta C., Gargaglioni, Luciane H., Dias, Mirela B.
Format: Article
Language:English
Subjects:
Central chemoreception
Glutamate
Hypercapnia
Hypothalamus
Orexin
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Summary:•Glutamate acting on metabotropic receptors in the LH/PFA inhibits CO2 drive to breath.•The tonic inhibition provided by glutamate in the LH/PFA occurs in wakefulness.•Glutamate metabotropic signaling in LH/PFA does not affect normocapnic breathing. It has been shown that the lateral hypothalamus/perifornical area (LH/PFA) exerts an important role on arousal-state variations of the central chemoreflex, but the mechanisms that underlie LH/PFA chemoreception are poorly understood. Here we asked whether glutamate inputs on metabotropic receptors in the LH/PFA modulate the hypercapnic ventilatory response. We studied the effects of microinjection of a glutamate metabotropic receptor (mGluR) antagonist ((+)-α-Methyl-4-carboxyphenylglycine; MCPG; 100 mM) and a selective Group II/III mGluR antagonist ((2S)-2-Amino-2-[(1S,2S)-2-carboxycycloprop-1-yl]-3-(xanth-9-yl) propanoic acid; LY341495; 5 mM) into the LH/PFA of conscious rats on ventilation in room air and in 7% CO2, during wakefulness and sleep, in the dark and light periods of the diurnal cycle. Microinjection of MCPG and LY341495 increased the hypercapnic ventilatory response in both the light and the dark period during wakefulness, but not during sleep, (p < 0.001). Our data suggest that glutamate, acting on Group II/III metabotropic receptors in the LH/PFA, exerts an inhibitory modulation of the hypercapnic ventilatory response in awake rats.
ISSN:1569-9048
1878-1519
DOI:10.1016/j.resp.2018.11.007