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DORSOMEDIAL HYPOTHALAMUS AND MEDULLARY RAPHE MEDIATE RESPIRATORY AROUSAL RESPONSES IN RATS
Author(s) -
Nalivaiko Eugene,
Beig Mirza I,
Xavier Carlos H,
Fontes Marco AP
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.1019.16
Subject(s) - raphe , respiratory rate , endocrinology , medicine , control of respiration , raphe nuclei , arousal , heart rate , respiratory system , chemistry , biology , neuroscience , serotonin , serotonergic , blood pressure , receptor
We aimed to reveal which brain areas are involved in the generation of tachypnoeic alerting responses. In male Wistar rats, we recorded heart rate (ECG telemetry) and respiration (plethysmography). Microinjection of muscimol or vehicle was made into the dorsomedial hypothalamus (DMH, Group 1, n=6) or the medullary raphe (Group 2, n=6). Basal respiratory rate (RR, 90±5 and 88±8 cpm) and heart rate (HR, 377±10 and 354±10 bpm) did not differ between groups. Alerting stimuli (tap, side move and gbright light) did not affect HR. In Group 1 (vehicle), RR raised by 105±27, 150±27 and 183±15.03 cpm after tap, move and light stimuli respectively. Inhibition of the DMH suppressed these responses by 92, 83 and 90% (tap/move/light). In Group 2 (vehicle), RR raised by 99±14, 118±23 and 165±20 cpm after tap, move and light stimuli respectively. Inhibition of the medullary raphe suppressed these responses by 81, 75, and 71% (tap/move/light). Blockade of the DMH or raphe region had no effect on basal levels of RR or HR. We conclude that DMH and MR are not involved in the control of respiratory rate at rest, but their integrity is essential for mediating tachypnoeic arousal responses. Support: NHMRC & Fapemig/CNPq