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.
Department of Pediatrics, Centre de Recherche, Hôpital Saint-François d'Assise, Laval University, Quebec City, Quebec, Canada G1L 3L5. Richard.Kinkead@crsfa.ulaval.ca
Richard
R
Kinkead
Olivier
O
Belzile
Roumiana
R
Gulemetova
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