title: Angiotensinergic and cholinergic receptors of the subfornical organ mediate sodium intake induced by GABAergic activation of the lateral parabrachial nucleus.
abstract: Bilateral injections of the GABA(A) agonist muscimol into the lateral parabrachial nucleus (LPBN) induce 0.3 M NaCl and water intake in satiated and normovolemic rats, a response reduced by intracerebroventricular (icv) administration of losartan or atropine (angiotensinergic type 1 (AT₁) and cholinergic muscarinic receptor antagonists, respectively). In the present study, we investigated the effects of the injections of losartan or atropine into the subfornical organ (SFO) on 0.3M NaCl and water intake induced by injections of muscimol into the LPBN. In addition, using intracellular calcium measurement, we also tested the sensitivity of SFO-cultured cells to angiotensin II (ANG II) and carbachol (cholinergic agonist). In male Holtzman rats with cannulas implanted bilaterally into the LPBN and into the SFO, injections of losartan (1 μg/0.1 μl) or atropine (2 nmol/0.1 μl) into the SFO almost abolished 0.3M NaCl and water intake induced by muscimol (0.5 nmol/0.2 μl) injected into the LPBN. In about 30% of the cultured cells of the SFO, carbachol and ANG II increased intracellular calcium concentration ([Ca²⁺](i)). Three distinct cell populations were found in the SFO, i.e., cells activated by either ANG II (25%) or carbachol (2.6%) or by both stimuli (2.3%). The results suggest that the activation of angiotensinergic and cholinergic mechanisms in the SFO is important for NaCl and water intake induced by the deactivation of LPBN inhibitory mechanisms with muscimol injections. They also show that there are cells in the SFO activated by both angiotensinergic and cholinergic stimuli, perhaps those involved in the responses to muscimol into the LPBN.
authors.affiliation: Department of Physiology and Pathology, School of Dentistry, São Paulo State University, UNESP, Araraquara, SP, Brazil; Department of Psychology, The Cardiovascular Center, University of Iowa, Iowa City, IA, USA; Department of Pharmacology, The Cardiovascular Center, University of Iowa, Iowa City, IA, USA.
authors.forename: C F
authors.initials: CF
authors.lastname: Roncari
authors.affiliation: Department of Physiology and Pathology, School of Dentistry, São Paulo State University, UNESP, Araraquara, SP, Brazil; Department of Psychology, The Cardiovascular Center, University of Iowa, Iowa City, IA, USA; Department of Pharmacology, The Cardiovascular Center, University of Iowa, Iowa City, IA, USA.
authors.forename: R B
authors.initials: RB
authors.lastname: David
authors.affiliation: Department of Psychology, The Cardiovascular Center, University of Iowa, Iowa City, IA, USA; Department of Pharmacology, The Cardiovascular Center, University of Iowa, Iowa City, IA, USA.
authors.forename: R F
authors.initials: RF
authors.lastname: Johnson
authors.affiliation: Department of Physiology and Pathology, School of Dentistry, São Paulo State University, UNESP, Araraquara, SP, Brazil.
authors.forename: P M
authors.initials: PM
authors.lastname: De Paula
authors.affiliation: Department of Physiology and Pathology, School of Dentistry, São Paulo State University, UNESP, Araraquara, SP, Brazil.
authors.forename: D S A
authors.initials: DS
authors.lastname: Colombari
authors.affiliation: Department of Physiology and Pathology, School of Dentistry, São Paulo State University, UNESP, Araraquara, SP, Brazil.
authors.forename: L A
authors.initials: LA
authors.lastname: De Luca
authors.affiliation: Department of Psychology, The Cardiovascular Center, University of Iowa, Iowa City, IA, USA; Department of Pharmacology, The Cardiovascular Center, University of Iowa, Iowa City, IA, USA.
authors.forename: A K
authors.initials: AK
authors.lastname: Johnson
authors.affiliation: Department of Physiology and Pathology, School of Dentistry, São Paulo State University, UNESP, Araraquara, SP, Brazil.
authors.forename: E
authors.initials: E
authors.lastname: Colombari
authors.affiliation: Department of Physiology and Pathology, School of Dentistry, São Paulo State University, UNESP, Araraquara, SP, Brazil. Electronic address: menani@foar.unesp.br.
authors.forename: J V
authors.initials: JV
authors.lastname: Menani
mesh_terms: D047228:Angiotensin II Type 1 Receptor Blockers / Q000494:pharmacology; D000818:Animals; D001285:Atropine / Q000494:pharmacology; D002478:Cells, Cultured; D004327:Drinking Behavior / Q000187:drug effects; D058785:GABA-A Receptor Agonists / Q000494:pharmacology; D019808:Losartan / Q000494:pharmacology; D008297:Male; D018727:Muscarinic Antagonists / Q000494:pharmacology; D009118:Muscimol / Q000494:pharmacology; D011149:Pons / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D011945:Receptors, Angiotensin / Q000378:metabolism; D011950:Receptors, Cholinergic / Q000378:metabolism; D018079:Receptors, GABA / Q000378:metabolism*; D017981:Receptors, Neurotransmitter / Q000378:metabolism*; D012965:Sodium Chloride / Q000008:administration & dosage*; D013356:Subfornical Organ / Q000187:drug effects / Q000378:metabolism*; D014867:Water
chemical_list: D047228:Angiotensin II Type 1 Receptor Blockers; D058785:GABA-A Receptor Agonists; D018727:Muscarinic Antagonists; D011945:Receptors, Angiotensin; D011950:Receptors, Cholinergic; D018079:Receptors, GABA; D017981:Receptors, Neurotransmitter; D014867:Water; D009118:Muscimol; D012965:Sodium Chloride; D001285:Atropine; D019808:Losartan
keywords: AT(1) receptor; muscarinic receptor; parabrachial nucleus; sodium appetite; subfornical organ