Tonic serotonergic control of ingestive behaviours in the pigeon (Columba livia): the role of the arcopallium.

Luciane Coutinho Azevedo Campanella, Amanda Alcaraz da Silva, Dayane Stephany Gellert, Caroline Parreira, Mayara Caldas Ramos, Marta A Paschoalini, José Marino-Neto

Department of Physiological Sciences, CCB, EEL-CTC, Federal University of Santa Catarina, 88040-900 Florianópolis SC, Brazil. lu.cda@hotmail.com

Behavioural brain research 2009 Dec 28

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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.

Citation

Luciane Coutinho Azevedo Campanella, Amanda Alcaraz da Silva, Dayane Stephany Gellert, Caroline Parreira, Mayara Caldas Ramos, Marta A Paschoalini, José Marino-Neto. Tonic serotonergic control of ingestive behaviours in the pigeon (Columba livia): the role of the arcopallium. Behavioural brain research. 2009 Dec 28;205(2):396-405