title: Rapid stimulation of sodium intake combining aldosterone into the 4th ventricle and the blockade of the lateral parabrachial nucleus.
abstract: Chronic infusion of aldosterone into the 4th ventricle (4th V) induces robust daily sodium intake, whereas acute injection of aldosterone into the 4th V produces no sodium intake. The inhibitory mechanism of the lateral parabrachial nucleus (LPBN) restrains sodium intake induced by different natriorexigenic stimuli and might affect the acute response to aldosterone into the 4th V. In the present study, 1.8% NaCl and water intake was tested in rats treated with acute injections of aldosterone into the 4th V combined with the blockade of the inhibitory mechanisms with injections of moxonidine (α2adrenergic/imidazoline agonist) or methysergide (a serotonergic antagonist) into the LPBN. Male Holtzman rats with stainless steel cannulas implanted in the 4th V and bilaterally in the LPBN were used. Aldosterone (250 or 500ng) into the 4th V combined with vehicle into the LPBN induced no 1.8% NaClintake compared to control (1.5±1.1 and 1.1±0.4, respectively, vs. vehicle into 4th V: 1.0±0.5ml/2h). However, aldosterone (250 or 500ng) into the 4th V combined with moxonidine (0.5nmol) into the LPBN induced strong ingestion of 1.8% NaCl (12.7±4.6 and 17.6±3.7ml/2h, respectively). Aldosterone (250ng) into the 4th V combined with methysergide (4μg) into the LPBN also induced 1.8% NaCl intake (17.6±5.4ml/2h). These data suggest that the inhibitory mechanisms of the LPBN counteract the facilitation of sodium intake produced by aldosterone injected into the 4th, restraining sodium intake in this condition.
authors.affiliation: Department of Physiology and Pathology, School of Dentistry of Araraquara, São Paulo State University, UNESP, Araraquara, SP, Brazil.
authors.forename: S
authors.initials: S
authors.lastname: Gasparini
authors.affiliation: Department of Physiology and Pathology, School of Dentistry of Araraquara, São Paulo State University, UNESP, Araraquara, SP, Brazil.
authors.forename: M R
authors.initials: MR
authors.lastname: Melo
authors.affiliation: Department of Physiology and Pathology, School of Dentistry of Araraquara, São Paulo State University, UNESP, Araraquara, SP, Brazil.
authors.forename: G F
authors.initials: GF
authors.lastname: Leite
authors.affiliation: Department of Physiology and Pathology, School of Dentistry of Araraquara, São Paulo State University, UNESP, Araraquara, SP, Brazil.
authors.forename: P A
authors.initials: PA
authors.lastname: Nascimento
authors.affiliation: Department of Physiology and Pathology, School of Dentistry of Araraquara, São Paulo State University, UNESP, Araraquara, SP, Brazil.
authors.forename: G M F
authors.initials: GMF
authors.lastname: Andrade-Franzé
authors.affiliation: Department of Physiology and Pathology, School of Dentistry of Araraquara, São Paulo State University, UNESP, Araraquara, SP, Brazil.
authors.forename: J V
authors.initials: JV
authors.lastname: Menani
authors.affiliation: Department of Physiology and Pathology, School of Dentistry of Araraquara, São Paulo State University, UNESP, Araraquara, SP, Brazil. Electronic address: eduardo.colombari@foar.unesp.br.
authors.forename: E
authors.initials: E
authors.lastname: Colombari
mesh_terms: D000450:Aldosterone / Q000008:administration & dosage*; D000818:Animals; D004326:Drinking; D004327:Drinking Behavior / Q000187:drug effects; D020546:Fourth Ventricle; D007093:Imidazoles / Q000008:administration & dosage; D007276:Injections, Intraventricular; D008297:Male; D065823:Parabrachial Nucleus / Q000187:drug effects* / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D017673:Sodium Chloride, Dietary
chemical_list: D007093:Imidazoles; D017673:Sodium Chloride, Dietary; D000450:Aldosterone; C043482:moxonidine
keywords: HSD2 neurons; hindbrain; mineralocorticoids; sodium appetite