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Orexinergic Modulation of Hypercapnic and Hypoxic Ventilatory Response in Toads
Author(s) -
Fonseca Elisa,
Dias Mirela,
Bicego Kenia,
Gargaglioni Luciane
Publication year - 2015
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.29.1_supplement.1033.6
Subject(s) - orexin , chemoreceptor , hypoxic ventilatory response , hypercarbia , suprachiasmatic nucleus , tidal volume , orexin receptor , medicine , endocrinology , hypoxia (environmental) , circadian rhythm , respiratory system , receptor , chemistry , neuropeptide , organic chemistry , oxygen , acidosis
Orexins (or hypocretins) play an important role in the modulation of respiratory control in mammals, but there are no data describing the role of the orexinergic system in the peripheral and central chemoreception of non‐mammalian vertebrates. Thus, the aim of this study was to examine the localization of orexin‐immunoreactive neurons in the brain of toads ( Rhinella schneideri ) and to investigate the contribution of orexin receptor‐1 (OX 1 R) to the hypoxic (5%O 2 ) and hypercarbic (5%CO 2 ) ventilatory responses during light and dark phases by intracerebroventricular (i.c.v.) injections of SB‐334867 (OX 1 R selective antagonist; dose: 5 and 10mM). Our results demonstrated that the SB‐334867 (10mM) attenuated the ventilatory response to hypercarbia during the dark phase in 54.8% by acting on tidal volume (vehicle: 172.9±5.3% of baseline; SB‐334867: 114.2±9.8% of baseline) and breathing frequency (vehicle: 218.3±24.1% of baseline; SB‐334867: 134.8±7.8% of baseline), while during the light phase, attenuated the ventilatory response to hypoxia in 51.6% by acting on tidal volume only (vehicle: 230.9±33.4% of baseline; SB‐334857: 127.5±4.9% of baseline). We conclude that in R. schneideri, orexinergic neurons are located in the suprachiasmatic nucleus and OX 1 R contributes to hypercarbic and hypoxic chemoreflex. Financial support: FAPESP, INCT‐FisComp and CNPq.