title: Distribution of serotonin 5-HT1A-binding sites in the brainstem and the hypothalamus, and their roles in 5-HT-induced sleep and ingestive behaviors in rock pigeons (Columba livia).
abstract: Serotonin 1A receptors (5-HT1ARs), which are widely distributed in the mammalian brain, participate in cognitive and emotional functions. In birds, 5-HT1ARs are expressed in prosencephalic areas involved in visual and cognitive functions. Diverse evidence supports 5-HT1AR-mediated 5-HT-induced ingestive and sleep behaviors in birds. Here, we describe the distribution of 5-HT1ARs in the hypothalamus and brainstem of birds, analyze their potential roles in sleep and ingestive behaviors, and attempt to determine the involvement of auto-/hetero-5-HT1ARs in these behaviors. In 6 pigeons, the anatomical distribution of [(3)H]8-OH-DPAT binding in the rostral brainstem and hypothalamus was examined. Ingestive/sleep behaviors were recorded (1h) in 16 pigeons pretreated with MM77 (a heterosynaptic 5-HT1AR antagonist; 23 or 69 nmol) for 20 min, followed by intracerebroventricular ICV injection of 5-HT (N:8; 150 nmol), 8-OH-DPAT (DPAT, a 5-HT1A,7R agonist, 30 nmol N:8) or vehicle. 5-HT- and DPAT-induced sleep and ingestive behaviors, brainstem 5-HT neuronal density and brain 5-HT content were examined in 12 pigeons, pretreated by ICV with the 5-HT neurotoxin 5,7-dihydroxytryptamine (5,7-DHT) or vehicle (N:6/group). The distribution of brainstem and diencephalic c-Fos immunoreactivity after ICV injection of 5-HT, DPAT or vehicle (N:5/group) into birds provided with or denied access to water is also described. 5-HT1ARs are concentrated in the brainstem 5-HTergic areas and throughout the periventricular hypothalamus, preoptic nuclei and circumventricular organs. 5-HT and DPAT produced a complex c-Fos expression pattern in the 5-HT1AR-enriched preoptic hypothalamus and the circumventricular organs, which are related to drinking and sleep regulation, but modestly affected c-Fos expression in 5-HTergic neurons. The 5-HT-induced ingestivebehaviors and the 5-HT- and DPAT-induced sleep behaviors were reduced by MM77 pretreatment. 5,7-DHT increased sleep per se, decreased tryptophan hydroxylase expression in the raphe nuclei and decreased prosencephalic 5-HT release but failed to affect 5-HT- or DPAT-induced drinking or sleep behavior. 5-HT- and DPAT-induced ingestive and sleep behaviors in pigeons appear to be mediated by heterosynaptic and/or non-somatodendritic presynaptic 5-HT1ARs localized to periventricular diencephalic circuits.
authors.affiliation: Department of Physiological Sciences, CCB, Federal University of Santa Catarina, 88040-900 Florianópolis, SC, Brazil. Electronic address: santos.ts@hotmail.com.
authors.forename: Tiago Souza
authors.initials: TS
authors.lastname: Dos Santos
authors.affiliation: Department of Physiological Sciences, CCB, Federal University of Santa Catarina, 88040-900 Florianópolis, SC, Brazil. Electronic address: jessica.kkruger@hotmail.com.
authors.forename: Jéssica
authors.initials: J
authors.lastname: Krüger
authors.affiliation: Department of Physiological Sciences, CCB, Federal University of Santa Catarina, 88040-900 Florianópolis, SC, Brazil. Electronic address: fmelleu@gmail.com.
authors.forename: Fernando Falkenburger
authors.initials: FF
authors.lastname: Melleu
authors.affiliation: C & O. Vogt Institute for Brain Research, Heinrich Heine University, 40225 Düsseldorf, Germany. Electronic address: christina.herold@uni-duesseldorf.de.
authors.forename: Christina
authors.initials: C
authors.lastname: Herold
authors.affiliation: Institute of Neuroscience and Medicine INM-1, Research Center Jülich, 52425 Jülich, Germany; Department of Psychiatry, Psychotherapy and Psychosomatics, RWTH Aachen University, 52074 Aachen, Germany; JARA - Translational Brain Medicine, 52074 Aachen, Germany. Electronic address: k.zilles@fz-juelich.de.
authors.forename: Karl
authors.initials: K
authors.lastname: Zilles
authors.affiliation: Department of Pharmacology, CCB, Federal University of Santa Catarina, 88040-900 Florianópolis, SC, Brazil. Electronic address: poli@ccb.ufsc.br.
authors.forename: Anicleto
authors.initials: A
authors.lastname: Poli
authors.affiliation: Institute for Cognitive Neuroscience, Faculty of Psychology, Ruhr University Bochum, 44780 Bochum, Germany. Electronic address: onur.guentuerkuen@ruhr-uni-bochum.de.
authors.forename: Onur
authors.initials: O
authors.lastname: Güntürkün
authors.affiliation: Department of Physiological Sciences, CCB, Federal University of Santa Catarina, 88040-900 Florianópolis, SC, Brazil; Institute of Biomedical Engineering, EEL-CTC, Federal University of Santa Catarina, 88040-900 Florianópolis, SC, Brazil. Electronic address: marino@ieb.ufsc.br.
authors.forename: José
authors.initials: J
authors.lastname: Marino-Neto
mesh_terms: D015116:5,7-Dihydroxytryptamine / Q000494:pharmacology; D017371:8-Hydroxy-2-(di-n-propylamino)tetralin / Q000494:pharmacology; D000818:Animals; D001665:Binding Sites; D001933:Brain Stem / Q000187:drug effects / Q000378:metabolism*; D010856:Columbidae / Q000378:metabolism*; D005247:Feeding Behavior / Q000187:drug effects; D005260:Female; D007031:Hypothalamus / Q000378:metabolism*; D008297:Male; D011903:Raphe Nuclei / Q000378:metabolism; D044282:Receptor, Serotonin, 5-HT1A / Q000378:metabolism*; D011985:Receptors, Serotonin; D012701:Serotonin / Q000378:metabolism; D017366:Serotonin Receptor Agonists / Q000494:pharmacology; D012890:Sleep / Q000187:drug effects* / Q000502:physiology; D000068776:Sleep Aids, Pharmaceutical
chemical_list: D011985:Receptors, Serotonin; D017366:Serotonin Receptor Agonists; D000068776:Sleep Aids, Pharmaceutical; D044282:Receptor, Serotonin, 5-HT1A; D015116:5,7-Dihydroxytryptamine; D012701:Serotonin; D017371:8-Hydroxy-2-(di-n-propylamino)tetralin
keywords: 5-HT-1A receptor; Cerebrospinal fluid; Drinking; Feeding; Serotonin; Sleep