title: Behavioral profile and Fos activation of serotonergic and non-serotonergic raphe neurons after central injections of serotonin in the pigeon (Columba livia).
abstract: Central injections of serotonin (5-HT) in food-deprived/refed pigeons evoke a sequence of hypophagic, hyperdipsic and sleep-like responses that resemble the postprandial behavioral sequence. Fasting-refeeding procedures affect sleep and drinking behaviors "per se". Here, we describe the behavioral profile and long-term food/water intake following intracerebroventricular (ICV) injections of 5-HT (50, 150, 300 nmol/2 μl) in free-feeding/drinking pigeons. The patterns of Fos activity (Fos+) in serotonergic (immunoreactive to tryptophan hydroxylase, TPH+) neurons after these treatments were also examined. 5-HT ICV injections evoked vehement drinking within 15 min, followed by an intense sleep. These effects did not extend beyond the first hour after treatment. 5-HT failed to affect feeding behavior consistently. The density of double-stained (Fos+/TPH+) cells was examined in 6 brainstem areas of pigeons treated with 5-HT (5-HTW) or vehicle. Another group received 5-HT and remained without access to water during 2h after treatment (5-HTØ). In the pontine raphe, Fos+ density correlated positively to sleep, and increased in both the 5-HTW and 5-HTØ animals. In the n. linearis caudalis, Fos+ and Fos+/TPH+ labeling was negatively correlated to sleep and was reduced in 5-HTØ animals. In the A8 region, Fos+/TPH+ labeling was reduced in 5-HTW and 5-HTØ animals, was positively correlated to food intake and negatively correlated to sleep. These data indicate that hyperdipsic and hypnogenic effects of ICV 5-HT in pigeons may result from the inhibition of a tonic activity of serotonergic neurons, which is possibly relevant to the control of postprandial behaviors, and that these relationships are shared functional traits of the serotonergic circuits in amniotes.
authors.affiliation: Department of Physiological Sciences, CCB, Federal University of Santa Catarina, 88040-900 Florianópolis, SC, Brazil.
authors.forename: Tiago Souza
authors.initials: TS
authors.lastname: dos Santos
authors.forename: Cristiane
authors.initials: C
authors.lastname: Meneghelli
authors.forename: Alexandre A
authors.initials: AA
authors.lastname: Hoeller
authors.forename: Marta Aparecida
authors.initials: MA
authors.lastname: Paschoalini
authors.forename: Lut
authors.initials: L
authors.lastname: Arckens
authors.forename: Cilene
authors.initials: C
authors.lastname: Lino-de-Oliveira
authors.forename: José
authors.initials: J
authors.lastname: Marino-Neto
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects*; D002452:Cell Count / Q000379:methods; D010856:Columbidae; D004305:Dose-Response Relationship, Drug; D004327:Drinking Behavior / Q000187:drug effects; D005247:Feeding Behavior / Q000187:drug effects; D005786:Gene Expression Regulation / Q000187:drug effects; D007276:Injections, Intraventricular / Q000379:methods; D009474:Neurons / Q000145:classification / Q000378:metabolism*; D016761:Oncogene Proteins v-fos / Q000378:metabolism*; D011903:Raphe Nuclei / Q000166:cytology*; D011930:Reaction Time / Q000187:drug effects; D012701:Serotonin / Q000378:metabolism* / Q000494:pharmacology*; D012890:Sleep / Q000187:drug effects; D014365:Tryptophan Hydroxylase / Q000378:metabolism
chemical_list: D016761:Oncogene Proteins v-fos; D012701:Serotonin; D014365:Tryptophan Hydroxylase