5-HT acting on 5-HT(1/2) receptors does not participate in the in vitro hypoxic respiratory depression.
The involvement of serotoninergic mechanisms in the central respiratory depression produced by hypoxia was studied in the newborn rat brainstem-spinal cord preparation. The respiratory frequency measured by the C4 ventral root activity was recorded. 5-HT (30 microM) superfusion elicited a rapid increase in respiratory frequency, prevented by a treatment with methysergide (a 5-HT(1/2) receptor antagonist) (40 microM). To investigate the possible participation of 5-HT in hypoxic respiratory depression, this concentration of methysergide was added to the bathing medium during hypoxia. Methysergide did not modify the decrease in respiratory frequency produced by hypoxia. In order to ensure that other 5-HT subtype receptors were not involved in hypoxic respiratory depression, 5-HT was added to the bath during hypoxic-methysergide tests; no effect on respiratory frequency was observed. These results suggest that in the newborn rat brainstem-spinal cord preparation, serotoninergic mechanisms are not involved in the elaboration of the in vitro respiratory response to hypoxia.
Cayetanot
F
F
Laboratoire de Neurophysiologie, Département Environnement Toxique Périnatal et Adaptations Physiologiques et Comportementales, EA 2088, Faculté de médecine, 3 rue des Louvels, 80036 cedex 1, Amiens, France. Florence.Cayetanot@sa.u-picardie.fr
Bodineau
L
L
Frugière
A
A
D000200:Action Potentials / Q000187:drug effects / Q000502:physiology; D000375:Aging / Q000502:physiology; D000818:Animals; D000831:Animals, Newborn / Q000033:anatomy & histology / Q000378:metabolism; D001238:Asphyxia Neonatorum / Q000378:metabolism / Q000503:physiopathology; D004525:Efferent Pathways / Q000187:drug effects* / Q000378:metabolism / Q000503:physiopathology; D006801:Humans; D002534:Hypoxia, Brain / Q000378:metabolism* / Q000503:physiopathology; D066298:In Vitro Techniques; D007231:Infant, Newborn; D008784:Methysergide / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D011985:Receptors, Serotonin / Q000187:drug effects* / Q000378:metabolism; D012125:Respiratory Center / Q000187:drug effects* / Q000378:metabolism / Q000503:physiopathology; D012143:Respiratory Physiological Phenomena / Q000187:drug effects*; D012701:Serotonin / Q000378:metabolism / Q000494:pharmacology*; D012702:Serotonin Antagonists / Q000494:pharmacology; D013116:Spinal Cord / Q000187:drug effects* / Q000378:metabolism / Q000503:physiopathology; D013126:Spinal Nerve Roots / Q000187:drug effects / Q000502:physiology
D011985:Receptors, Serotonin; D012702:Serotonin Antagonists; D012701:Serotonin; D008784:Methysergide