title: Activation of μ opioid receptors in the LPBN facilitates sodium intake in rats.
abstract: Important inhibitory mechanisms for the control of water and sodium intake are present in the lateral parabrachial nucleus (LPBN). Opioid receptors are expressed by LPBN neurons and injections of β-endorphin (nonspecific opioid receptor agonist) in this area induce 0.3M NaCl and water intake in satiated rats. In the present study, we investigated the effects of the injections of endomorphin-1 (μ opioid receptor agonist) alone or combined with the blockade of μ, κ or δ opioid receptors into the LPBN on 0.3M NaCl and water intake induced by subcutaneous injections of the diuretic furosemide (FURO) combined with low dose of the angiotensin converting enzyme inhibitor captopril (CAP). Male Holtzman rats with stainless steel cannulas implanted bilaterally in the LPBN were used. Bilateral injections of endomorphin-1 (0.1, 0.25, 0.5, 1.0, 2.0 and 4.0nmol/0.2μl) into the LPBN increased 0.3M NaCl and water intake induced by FURO+CAP. The previous blockade of μ opioid receptor with CTAP (1.0nmol/0.2μl) into the LPBN reduced the effect of endomorphin-1 on FURO+CAP-induced 0.3M NaCl. GNTI (κ opioid receptor antagonist; 2.0nmol/0.2μl) and naltrindole (δ opioid receptor antagonist; 2.0nmol/0.2μl) injected into the LPBN did not change the effects of endomorphin-1 on FURO+CAP-induced 0.3M NaCl. The results suggest that μ opioid receptors in the LPBN are involved in the control of sodium intake.
authors.affiliation: Department of Physiology and Pathology, School of Dentistry, São Paulo State University, UNESP, Araraquara, SP 14801-903, Brazil.
authors.forename: Carolina G
authors.initials: CG
authors.lastname: Pavan
authors.affiliation: Department of Physiology and Pathology, School of Dentistry, São Paulo State University, UNESP, Araraquara, SP 14801-903, Brazil.
authors.forename: Camila F
authors.initials: CF
authors.lastname: Roncari
authors.affiliation: Department of Physiology and Pathology, School of Dentistry, São Paulo State University, UNESP, Araraquara, SP 14801-903, Brazil.
authors.forename: Silas P
authors.initials: SP
authors.lastname: Barbosa
authors.affiliation: Department of Physiology and Pathology, School of Dentistry, São Paulo State University, UNESP, Araraquara, SP 14801-903, Brazil.
authors.forename: Patrícia 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 14801-903, Brazil.
authors.forename: Débora 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 14801-903, Brazil.
authors.forename: Laurival A
authors.initials: LA
authors.lastname: De Luca
authors.affiliation: Department of Physiology and Pathology, School of Dentistry, São Paulo State University, UNESP, Araraquara, SP 14801-903, Brazil.
authors.forename: Eduardo
authors.initials: E
authors.lastname: Colombari
authors.affiliation: Department of Physiology and Pathology, School of Dentistry, São Paulo State University, UNESP, Araraquara, SP 14801-903, Brazil. Electronic address: menani@foar.unesp.br.
authors.forename: José V
authors.initials: JV
authors.lastname: Menani
mesh_terms: D000701:Analgesics, Opioid / Q000494:pharmacology; D000806:Angiotensin-Converting Enzyme Inhibitors / Q000494:pharmacology; D000818:Animals; D001069:Appetite Regulation / Q000187:drug effects / Q000502:physiology*; D004232:Diuretics / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004326:Drinking / Q000187:drug effects / Q000502:physiology*; D060766:Drinking Water; D008297:Male; D009292:Narcotic Antagonists / Q000494:pharmacology; D009842:Oligopeptides / Q000494:pharmacology; D065823:Parabrachial Nucleus / Q000187:drug effects / Q000378:metabolism*; D017207:Rats, Sprague-Dawley; D017465:Receptors, Opioid, delta / Q000037:antagonists & inhibitors / Q000378:metabolism; D017473:Receptors, Opioid, kappa / Q000037:antagonists & inhibitors / Q000378:metabolism; D017450:Receptors, Opioid, mu / Q000819:agonists / Q000037:antagonists & inhibitors / Q000378:metabolism*; D012965:Sodium Chloride; D012982:Sodium, Dietary
chemical_list: D000701:Analgesics, Opioid; D000806:Angiotensin-Converting Enzyme Inhibitors; D004232:Diuretics; D060766:Drinking Water; D009292:Narcotic Antagonists; D009842:Oligopeptides; D017465:Receptors, Opioid, delta; D017473:Receptors, Opioid, kappa; D017450:Receptors, Opioid, mu; D012982:Sodium, Dietary; C105293:endomorphin 1; D012965:Sodium Chloride
keywords: Endomorphin; Parabrachial nucleus; Sodium appetite; μ Opioid receptor