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The orexin receptor 1 (OX1R) in the rostral medullary raphe contributes to the hypercapnic chemoreflex in wakefulness, during the dark (active) period of the diurnal cycle
Author(s) -
Dias Mirela B,
Li Aihua,
Nattie Eugene E
Publication year - 2010
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.24.1_supplement.1026.8
Subject(s) - wakefulness , raphe , orexin , raphe nuclei , central chemoreceptors , medicine , control of respiration , endocrinology , serotonergic , neuroscience , biology , respiratory system , serotonin , neuropeptide , receptor , electroencephalography
The orexin system plays an important role in the hypercapnic chemoreflex during wakefulness, and the OX 1 R in the retrotrapezoid nucleus (RTN), one central chemoreceptor site, participates in this reflex. We hypothesized that OX 1 Rs at the rostral medullary raphe (rMR) contribute to central chemoreception. In unanesthetized rats, ventilation was recorded in a whole body plethysmograph. We studied the effects on ventilation in air and 7%CO 2 of focal antagonism of OX 1 R in the rMR by microdialysis of SB‐334867 in rats during wakefulness and NREM sleep, separately under dark and light periods. During wakefulness in the dark period, but not in the light period, SB‐334867 caused a 16% reduction of respiratory response to CO 2 (167.1 ± 5.6 ml/100g/min) compared with vehicle (195.5 ± 7.2 ml/100g/min) (P< 0.01). There was no significant effect in sleep. The basal ventilation, body temperature and metabolic rate were not affected. No effect was observed in a separate group which had the probes misplaced. In the RTN, the focal antagonism of OX 1 R caused a 30% attenuation of the CO 2 response in wakefulness, a greater effect than that observed in this study. However, the putative chemosensitive cells in the raphe may be distributed over a wider region than those in the RTN. We conclude that OX 1 Rs in the rostral medullary raphe contribute to the hypercapnic chemoreflex in wakefulness, during the dark period in rats. (HL 28066)