title: Injections of the of the α1-adrenoceptor antagonist prazosin into the median raphe nucleus increase food intake and Fos expression in orexin neurons of free-feeding rats.
abstract: Previously, we showed that the blockade of α1-adrenoreceptors in the median raphe nucleus (MnR) increased food intake in free-feeding rats, indicating that adrenergic mechanisms in the MnR participate in the regulation of food intake. However, the impact of such a pharmacological manipulation on other neural circuits related to food intake remains unknown. In the current study, we sought to identify forebrain regions which are responsive to α1-adrenergic receptor blockade and presumably involved in the modulation of the feeding response. For this purpose, we examined the induction of c-Fos immunoreactivity in forebrain structures following injections of the α1-adrenoceptor antagonist prazosin into the MnR of free-feeding rats. To determine the chemical identity of hypothalamic c-Fos-positive cells, we then conducted double-label immunohistochemistry for Fos/orexin (OX) or Fos/melanin-concentrating hormone (MCH). Finally, we combined anterograde tracing from the MnR with immunohistochemical detection of orexin. Prazosin injections into the MnR significantly increased food intake. The ingestive response was accompanied by an increase in Fos expression in the basolateral amygdala (BLA) and lateral hypothalamic area (LHA). In the LHA, Fos expression occurred in neurons expressing OX, but not MCH. Combined anterograde tracing experiments revealed that LHA OX neurons are prominently targeted by MnR axons. These findings suggest that intra-MnR injection of prazosin, via activation of orexinergic neurons in the LHA and non-orexinergic neurons in the BLA, evoked a motivational response toward food intake.
authors.affiliation: Department of Natural Sciences, Center of Exact and Natural Sciences - CCEN, Regional University of Blumenau (FURB), 89030-903, Blumenau, SC, Brazil. Electronic address: edu_simao@yahoo.com.br.
authors.forename: Eduardo Simão da
authors.initials: ESD
authors.lastname: Silva
authors.affiliation: Department of Physiological Sciences, Center of Biological Sciences - CCB, Federal University of Santa Catarina (UFSC), 88040-970, Florianópolis, SC, Brazil. Electronic address: rafaelappelflores@gmail.com.
authors.forename: Rafael Appel
authors.initials: RA
authors.lastname: Flores
authors.affiliation: Department of Physiological Sciences, Center of Biological Sciences - CCB, Federal University of Santa Catarina (UFSC), 88040-970, Florianópolis, SC, Brazil. Electronic address: andersonsavaris@hotmail.com.
authors.forename: Anderson Savaris
authors.initials: AS
authors.lastname: Ribas
authors.affiliation: Department of Physiological Sciences, Center of Biological Sciences - CCB, Federal University of Santa Catarina (UFSC), 88040-970, Florianópolis, SC, Brazil. Electronic address: anapaulataschetto@gmail.com.
authors.forename: Ana Paula
authors.initials: AP
authors.lastname: Taschetto
authors.affiliation: Department of Physiological Sciences, Center of Biological Sciences - CCB, Federal University of Santa Catarina (UFSC), 88040-970, Florianópolis, SC, Brazil. Electronic address: m.serralvo@ufsc.br.
authors.forename: Moacir Serralvo
authors.initials: MS
authors.lastname: Faria
authors.affiliation: Department of Physiology & Biophysics, Institute of Biomedical Sciences, University of São Paulo, 05508-900, São Paulo, SP, Brazil. Electronic address: lbueno@icb.usp.br.
authors.forename: Leandro Bueno
authors.initials: LB
authors.lastname: Lima
authors.affiliation: Department of Physiology & Biophysics, Institute of Biomedical Sciences, University of São Paulo, 05508-900, São Paulo, SP, Brazil. Electronic address: metzger@icb.usp.br.
authors.forename: Martin
authors.initials: M
authors.lastname: Metzger
authors.affiliation: Department of Physiology & Biophysics, Institute of Biomedical Sciences, University of São Paulo, 05508-900, São Paulo, SP, Brazil. Electronic address: jdonato@icb.usp.br.
authors.forename: José
authors.initials: J
authors.lastname: Donato
authors.affiliation: Department of Physiological Sciences, Center of Biological Sciences - CCB, Federal University of Santa Catarina (UFSC), 88040-970, Florianópolis, SC, Brazil. Electronic address: marta@ccb.ufsc.br.
authors.forename: Marta Aparecida
authors.initials: MA
authors.lastname: Paschoalini
mesh_terms: D058668:Adrenergic alpha-1 Receptor Antagonists / Q000008:administration & dosage*; D000818:Animals; D066272:Basolateral Nuclear Complex / Q000378:metabolism; D004435:Eating; D007028:Hypothalamic Hormones / Q000378:metabolism; D007031:Hypothalamus / Q000378:metabolism; D008297:Male; D008543:Melanins / Q000378:metabolism; D009474:Neurons / Q000378:metabolism*; D000068797:Orexins / Q000378:metabolism; D010907:Pituitary Hormones / Q000378:metabolism; D011224:Prazosin / Q000008:administration & dosage*; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism; D011903:Raphe Nuclei / Q000187:drug effects / Q000502:physiology*; D017208:Rats, Wistar; D018340:Receptors, Adrenergic, alpha-1 / Q000502:physiology*
chemical_list: D058668:Adrenergic alpha-1 Receptor Antagonists; D007028:Hypothalamic Hormones; D008543:Melanins; D000068797:Orexins; D010907:Pituitary Hormones; D016760:Proto-Oncogene Proteins c-fos; D018340:Receptors, Adrenergic, alpha-1; C019463:melanin-concentrating hormone; D011224:Prazosin
keywords: Basolateral amygdala; Feeding behavior; Lateral hypothalamic area; Median raphe nucleus; Orexin; α1-adrenoreceptor