Serotonergic modulation of respiratory motor output during tadpole development.
To test the hypothesis that serotonin (5-hydroxytryptamine; 5-HT)-receptor activation elicits age-dependent changes in respiratory motor output, we compared the effects of 5-HT bath application (5-HT concentration = 0.5-25 microM) onto in vitro brain stem preparations from pre- and postmetamorphic bullfrog tadpoles. Recording of motor output related to gill and lung ventilation showed that 5-HT elicits a dose-dependent depression of gill burst frequency in both groups. In contrast, the lung burst frequency response was stage dependent; an increase in lung burst frequency at low 5-HT concentration (< or =0.5 microM) was observed only in the postmetamorphic group. Higher 5-HT concentrations decreased lung burst frequency in all preparations. Gill burst frequency attenuation is mediated (at least in part) by 5-HT(1A)-receptor activation in an age-dependent fashion. We conclude that serotonergic modulation of respiratory motor output 1) changes during tadpole development and 2) is distinct for gill and lung ventilation.
Kinkead
Richard
R
Department of Pediatrics, Centre de Recherche, Hôpital Saint-François d'Assise, Laval University, Quebec City, Quebec, Canada G1L 3L5. Richard.Kinkead@crsfa.ulaval.ca
Belzile
Olivier
O
Gulemetova
Roumiana
R
D000818:Animals; D001933:Brain Stem / Q000187:drug effects / Q000254:growth & development; D004305:Dose-Response Relationship, Drug; D004594:Electrophysiology; D005880:Gills / Q000502:physiology; D066298:In Vitro Techniques; D007814:Larva / Q000187:drug effects; D008168:Lung / Q000502:physiology; D009994:Osmolar Concentration; D011892:Rana catesbeiana / Q000502:physiology*; D011985:Receptors, Serotonin / Q000502:physiology; D044263:Receptors, Serotonin, 5-HT1; D012119:Respiration / Q000187:drug effects; D012132:Respiratory Muscles / Q000187:drug effects* / Q000502:physiology; D012701:Serotonin / Q000008:administration & dosage / Q000494:pharmacology*
D011985:Receptors, Serotonin; D044263:Receptors, Serotonin, 5-HT1; D012701:Serotonin