title: Gabaergic and opioid receptors mediate the facilitation of NaCl intake induced by α₂-adrenergic activation in the lateral parabrachial nucleus.
abstract: Alpha2-adrenergic, gabaergic or opioidergic activation in the lateral parabrachial nucleus (LPBN) increases sodium intake. In the present study, we investigated the effects of single or combined blockade of opioidergic and gabaergic receptors in the LPBN on the increase of 0.3M NaCl intake induced by α2-adrenoceptor activation in the LPBN. Male Holtzman rats (n=5-9/group) with cannulas implanted bilaterally in the LPBN were treated with the diuretic furosemide (10 mg/kg b wt.) combined with low dose of the angiotensin converting enzyme inhibitor captopril (5 mg/kg b wt.) subcutaneously. Bilateral injections of moxonidine (alpha2-adrenergic/imidazoline receptor agonist, 0.5 nmol) into the LPBN increased furosemide+captopril-induced 0.3M NaCl intake (25.8±1.4, vs. vehicle: 3.8±1.1 ml/60 min). The opioidergic receptor antagonist naloxone (100 nmol) or the GABAA receptor antagonist bicuculline (5 nmol) injected into the LPBN partially reduced the increase of 0.3M NaCl intake produced by LPBN moxonidine (11.8±4.0 and 22.8±4.5, respectively, vs. vehicle+moxonidine: 31.6±4.0 ml/60 min, respectively). Similar to the treatment with each antagonist alone, the combined injections of naloxone (100 nmol) and bicuculline (5 nmol) into the LPBN also partially reduced moxonidine effects on 0.3M NaCl intake (15.5±6.5 ml/60 min). The GABAB receptor antagonist saclofen (5 nmol) injected into the LPBN did not change the effects of moxonidine on 0.3M NaCl intake (24.3±7.8 ml/120 min). These results suggest that the increase of 0.3M NaCl intake by α2-adrenergic receptor activation in the LPBN is partially dependent on GABAA and opioid receptor activation in this area.
authors.affiliation: Departament of Physiology and Pathology, School of Dentistry, UNESP, Araraquara-SP, 14801-903, Brazil. Electronic address: carina.andrade@foar.unesp.br.
authors.forename: C A F
authors.initials: CA
authors.lastname: Andrade
authors.affiliation: Department of Biological Sciences, DECBI-NUPEB, Federal University of Ouro Preto, Ouro Preto, MG, Brazil.
authors.forename: L B
authors.initials: LB
authors.lastname: De Oliveira
authors.affiliation: Departament of Physiology and Pathology, School of Dentistry, UNESP, Araraquara-SP, 14801-903, Brazil.
authors.forename: G M F
authors.initials: GM
authors.lastname: Andrade-Franzé
authors.affiliation: Departament of Physiology and Pathology, School of Dentistry, UNESP, Araraquara-SP, 14801-903, Brazil.
authors.forename: L A
authors.initials: LA
authors.lastname: De Luca
authors.affiliation: Departament of Physiology and Pathology, School of Dentistry, UNESP, Araraquara-SP, 14801-903, Brazil.
authors.forename: Débora S A
authors.initials: DS
authors.lastname: Colombari
authors.affiliation: Departament of Physiology and Pathology, School of Dentistry, UNESP, Araraquara-SP, 14801-903, Brazil.
authors.forename: J V
authors.initials: JV
authors.lastname: Menani
mesh_terms: D000818:Animals; D000959:Antihypertensive Agents / Q000494:pharmacology; D001418:Baclofen / Q000494:pharmacology; D001640:Bicuculline / Q000494:pharmacology; D002216:Captopril / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005665:Furosemide / Q000494:pharmacology; D058787:GABA-A Receptor Antagonists / Q000494:pharmacology; D058786:GABA-B Receptor Agonists / Q000494:pharmacology; D007093:Imidazoles / Q000494:pharmacology; D008297:Male; D009270:Naloxone / Q000494:pharmacology; D009292:Narcotic Antagonists / Q000494:pharmacology; D065823:Parabrachial Nucleus / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D018341:Receptors, Adrenergic, alpha-2 / Q000378:metabolism*; D018079:Receptors, GABA / Q000378:metabolism*; D011957:Receptors, Opioid / Q000378:metabolism*; D012965:Sodium Chloride / Q000378:metabolism*; D049994:Sodium Potassium Chloride Symporter Inhibitors / Q000494:pharmacology
chemical_list: D000959:Antihypertensive Agents; D004791:Enzyme Inhibitors; D058787:GABA-A Receptor Antagonists; D058786:GABA-B Receptor Agonists; D007093:Imidazoles; D009292:Narcotic Antagonists; D018341:Receptors, Adrenergic, alpha-2; D018079:Receptors, GABA; D011957:Receptors, Opioid; D049994:Sodium Potassium Chloride Symporter Inhibitors; D009270:Naloxone; D012965:Sodium Chloride; D005665:Furosemide; D002216:Captopril; C043482:moxonidine; D001418:Baclofen; D001640:Bicuculline
keywords: Adrenergic; Dehydration; GABA; Opioid; Sodium appetite; Thirst