Serotoninergic receptors in the anteroventral preoptic region modulate the hypoxic ventilatory response.
Hypothalamus is a site of integration of the hypoxic and thermal stimuli on breathing and there is evidence that serotonin (5-HT) receptors in the anteroventral preoptic region (AVPO) mediate hypoxic hypothermia. Once 5-HT is involved in the hypoxic ventilatory response (HVR), we investigated the participation of the 5-HT receptors (5-HT1, 5-HT2 and 5-HT7) in the AVPO in the HVR. To this end, pulmonary ventilation (V(E)) of rats was measured before and after intra-AVPO microinjection of methysergide (a 5-HT1 and 5-HT2 receptor antagonist), WAY-100635 (a 5-HT1A receptor antagonist) and SB-269970 (a 5-HT7 receptor antagonist), followed by 60 min of hypoxia exposure (7% O2). Intra-AVPO microinjection of vehicles or 5-HT antagonists did not change V(E) during normoxic conditions. Exposure of rats to 7% O2 evoked typical hypoxia-induced hyperpnea after vehicle microinjection, which was not affected by methysergide. WAY-100635 and SB-269970 treatment caused an increased HVR, due to a higher tidal volume. Therefore, the current data provide the evidence that 5-HT acting on 5-HT1A and 5-HT7 receptors in the AVPO exert an inhibitory modulation on the HVR.
Gargaglioni
Luciane H
LH
Department of Animal Morphology and Physiology, State University of Sao Paulo at Jaboticabal, SP, Brazil. lucihel@fcav.unesp.br
Bícego
Kênia C
KC
Nucci
Tatiane B
TB
Branco
Luiz G S
LG
D000704:Analysis of Variance; D000818:Animals; D000860:Hypoxia / Q000188:drug therapy / Q000503:physiopathology*; D008297:Male; D008784:Methysergide / Q000494:pharmacology; D008845:Microinjections / Q000379:methods; D011301:Preoptic Area / Q000187:drug effects / Q000502:physiology*; D012123:Pulmonary Ventilation / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D011985:Receptors, Serotonin / Q000502:physiology*; D012702:Serotonin Antagonists / Q000494:pharmacology
D011985:Receptors, Serotonin; D012702:Serotonin Antagonists; D008784:Methysergide