Tonic serotonergic control of ingestive behaviours in the pigeon (Columba livia): the role of the arcopallium.
This study examined the acute changes in feeding and drinking behaviours of free-feeding and free-drinking pigeons, in response to local injections of metergoline (MET, 5-HT(1/2) receptor antagonist; 7 and 20 nmol), GR46611 (GR, 5-HT(1B/1D) agonist; 2 and 6 nmol) or vehicle, into two components of the arcopallium: the nucleus taeniae of the amygdala (TnA) and the arcopallium intermedium (AI). In the TnA, the highest MET dose elicited a short-lived hyperphagy, without affecting drinking or non-ingestive behaviours during the first hour after injection. In contrast, all MET doses promptly increased drinking when injected in the AI, without affecting feeding; this effect was still evident 3 and 24 h after the treatment. When injected in the TnA, the highest GR dose promptly increased both food and water intake; these effects persisted 24 h after the treatments. GR injections in the AI evoked long-lasting increases in drinking, but not in feeding. Injections of these drugs into other arcopallial nuclei evoked no significant ingestive effects. These data indicate the presence of a tonic inhibitory influence of serotonergic inputs, partially mediated by 5-HT(1B/1D) receptors, on feeding- and drinking-related TnA circuits and on mechanisms controlling drinking in the AI. Compared to data from the rodent medial amygdala, our results suggest that a tonic inhibitory 5-HTergic control of feeding (but not drinking) behaviour, mediated by 5-HT(1/2) receptors and exerted in the medial amygdaloid area, may represent a broadly conserved functional attribute in the amniote brain, but probably involves many important taxa-specific neural mechanisms.
Campanella
Luciane Coutinho Azevedo
LC
Department of Physiological Sciences, CCB, EEL-CTC, Federal University of Santa Catarina, 88040-900 Florianópolis SC, Brazil. lu.cda@hotmail.com
da Silva
Amanda Alcaraz
AA
Gellert
Dayane Stephany
DS
Parreira
Caroline
C
Ramos
Mayara Caldas
MC
Paschoalini
Marta A
MA
Marino-Neto
José
J
D000178:Acrylamides / Q000008:administration & dosage / Q000494:pharmacology; D000679:Amygdala / Q000187:drug effects / Q000502:physiology*; D000704:Analysis of Variance; D000818:Animals; D001921:Brain / Q000187:drug effects / Q000502:physiology*; D002404:Catheterization; D010856:Columbidae; D004305:Dose-Response Relationship, Drug; D004326:Drinking / Q000187:drug effects / Q000502:physiology*; D004435:Eating / Q000187:drug effects / Q000502:physiology*; D007211:Indoles / Q000008:administration & dosage / Q000494:pharmacology; D008297:Male; D008711:Metergoline / Q000008:administration & dosage / Q000494:pharmacology; D044302:Receptor, Serotonin, 5-HT1B / Q000378:metabolism; D044346:Receptor, Serotonin, 5-HT1D / Q000378:metabolism; D044263:Receptors, Serotonin, 5-HT1 / Q000378:metabolism*; D044348:Receptors, Serotonin, 5-HT2 / Q000378:metabolism*; D058825:Serotonin 5-HT1 Receptor Agonists; D058829:Serotonin 5-HT1 Receptor Antagonists; D058830:Serotonin 5-HT2 Receptor Antagonists; D012702:Serotonin Antagonists / Q000008:administration & dosage / Q000494:pharmacology; D017366:Serotonin Receptor Agonists / Q000008:administration & dosage / Q000494:pharmacology; D013997:Time Factors
D000178:Acrylamides; C119994:GR 46611; D007211:Indoles; D044302:Receptor, Serotonin, 5-HT1B; D044346:Receptor, Serotonin, 5-HT1D; D044263:Receptors, Serotonin, 5-HT1; D044348:Receptors, Serotonin, 5-HT2; D058825:Serotonin 5-HT1 Receptor Agonists; D058829:Serotonin 5-HT1 Receptor Antagonists; D058830:Serotonin 5-HT2 Receptor Antagonists; D012702:Serotonin Antagonists; D017366:Serotonin Receptor Agonists; D008711:Metergoline