title: Temporal dissociation between sodium depletion and sodium appetite appearance: Involvement of inhibitory and stimulatory signals.
abstract: Our aim was to analyze the participation of inhibitory and stimulatory signals in the temporal dissociation between sodium depletion (SD) induced by peritoneal dialysis (PD) and the appearance of sodium appetite (SA), particularly 2h after PD, when the rats are hypovolemic/natremic but SA is not evident. We investigated the effects of bilateral injections of the serotonin (5-HT) receptor antagonist, methysergide, into the lateral parabrachial nucleus (LPBN) on hypertonic NaCl and water intake 2h vs. 24h after PD. We also studied plasma renin activity (PRA) and aldosterone (ALDO) concentration 2h vs. 24h after PD. Additionally, we combined the analysis of brain Fos immunoreactivity (Fos-ir) with the detection of double immunoreactivity in 5HT and oxytocinergic (OT) cells 2h after PD. Bilateral LPBN injections of methysergide (4μg/200nl at each site) increased NaCl intake when tested 2h after PD compared to controls. We found a significant increase in PRA and ALDO concentration after PD but no differences between 2 and 24h after PD. We also found for the first time a significant increase 2h after PD in the number of Fos-ir neurons in the brainstem nuclei that have been shown to be involved in the inhibition of SA. In summary, the results show that 5HT-mechanisms in the LPBN modulate sodium intake during the delay of SA when the renin angiotensin aldosterone system (RAAS) is increased. In addition, the activation of brainstem areas previously associated with the satiety phase of SA is in part responsible for the temporal dissociation between SD and behavioral arousal.
authors.affiliation: Department of Physiology, School of Medicine of Ribeirao Preto, University of Sao Paulo, Sao Paulo, Brazil.
authors.forename: L O
authors.initials: LO
authors.lastname: Margatho
authors.affiliation: Instituto de Investigación Médica Mercedes y Martín Ferreyra (INIMEC-CONICET-Universidad Nacional de Córdoba), Casilla de Correo, 389-5000 Córdoba, Argentina.
authors.forename: C Y
authors.initials: CY
authors.lastname: Porcari
authors.affiliation: Instituto de Investigación Médica Mercedes y Martín Ferreyra (INIMEC-CONICET-Universidad Nacional de Córdoba), Casilla de Correo, 389-5000 Córdoba, Argentina.
authors.forename: A F
authors.initials: AF
authors.lastname: Macchione
authors.affiliation: Department of Physiology, School of Medicine of Ribeirao Preto, University of Sao Paulo, Sao Paulo, Brazil.
authors.forename: G D
authors.initials: GD
authors.lastname: da Silva Souza
authors.affiliation: Instituto de Investigación Médica Mercedes y Martín Ferreyra (INIMEC-CONICET-Universidad Nacional de Córdoba), Casilla de Correo, 389-5000 Córdoba, Argentina.
authors.forename: X E
authors.initials: XE
authors.lastname: Caeiro
authors.affiliation: Department of Physiology, School of Medicine of Ribeirao Preto, University of Sao Paulo, Sao Paulo, Brazil.
authors.forename: J
authors.initials: J
authors.lastname: Antunes-Rodrigues
authors.affiliation: Instituto de Investigación Médica Mercedes y Martín Ferreyra (INIMEC-CONICET-Universidad Nacional de Córdoba), Casilla de Correo, 389-5000 Córdoba, Argentina; Facultad de Ciencias Exactas Físicas y Naturales, Universidad Nacional de Córdoba, Córdoba, Argentina.
authors.forename: L
authors.initials: L
authors.lastname: Vivas
authors.affiliation: Instituto de Investigación Médica Mercedes y Martín Ferreyra (INIMEC-CONICET-Universidad Nacional de Córdoba), Casilla de Correo, 389-5000 Córdoba, Argentina. Electronic address: agodino@immf.uncor.edu.
authors.forename: A
authors.initials: A
authors.lastname: Godino
mesh_terms: D000284:Administration, Oral; D000450:Aldosterone / Q000097:blood; D000818:Animals; D001066:Appetite / Q000187:drug effects / Q000502:physiology*; D001921:Brain / Q000378:metabolism*; D004327:Drinking Behavior / Q000187:drug effects / Q000502:physiology*; D005947:Glucose / Q000008:administration & dosage; D008297:Male; D008784:Methysergide / Q000494:pharmacology; D016761:Oncogene Proteins v-fos / Q000378:metabolism; D010121:Oxytocin / Q000378:metabolism; D065823:Parabrachial Nucleus / Q000187:drug effects; D051381:Rats; D017208:Rats, Wistar; D012083:Renin / Q000097:blood; D012462:Saline Solution, Hypertonic / Q000008:administration & dosage; D012701:Serotonin / Q000378:metabolism; D012702:Serotonin Antagonists / Q000494:pharmacology; D012964:Sodium / Q000378:metabolism*; D013997:Time Factors; D014882:Water-Electrolyte Balance
chemical_list: D016761:Oncogene Proteins v-fos; D012462:Saline Solution, Hypertonic; D012702:Serotonin Antagonists; D012701:Serotonin; D000450:Aldosterone; D010121:Oxytocin; D012964:Sodium; D012083:Renin; D005947:Glucose; D008784:Methysergide
keywords: lateral parabrachial nucleus; serotonergic system; sodium appetite; sodium depletion; temporary dissociation