Central muscarinic and LPBN mechanisms on sodium intake

• Published in: Brain research bulletin Vol. 144; pp. 14 - 20
• Main Authors: Anesio, Augusto, Barbosa, Silas Pereira, De Luca, Laurival A., de Paula, Patrícia Maria, Colombari, Débora S.A., Colombari, Eduardo, Andrade, Carina A.F., Menani, José V.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.01.2019
• Subjects: Animals; Cholinergic; Diamines - pharmacology; Drinking - drug effects; Drinking Behavior - drug effects; Imidazoles - pharmacology; Male; Methoctramine; Muscarinic Agonists - pharmacology; Muscarinic Antagonists - pharmacology; Muscimol - pharmacology; NaCl intake; Parabrachial; Parabrachial Nucleus - drug effects; Parabrachial Nucleus - metabolism; Pilocarpine - pharmacology; Pirenzepine; Pirenzepine - pharmacology; Rats; Rats, Sprague-Dawley; Receptor, Muscarinic M1 - drug effects; Receptor, Muscarinic M1 - metabolism; Receptor, Muscarinic M2 - drug effects; Receptor, Muscarinic M2 - metabolism; Sodium appetite; Sodium Chloride - metabolism; Sodium, Dietary; IU’s; MnPo; s.c; CCK; b.w; i.p; LV; OVLT; NTS; Methoctramine; Cholinergic; AP; Parabrachial; NaCl intake; LPBN; Sodium appetite; CRF; GABA; i.c.v; Pirenzepine; SFO; AT1
• ISSN: 0361-9230; 1873-2747
• DOI: 10.1016/j.brainresbull.2018.10.011

•Forebrain M1 and M2 receptor activation may facilitate NaCl intake.•Parabrachial nucleus inhibits the natriorexigenic effect of cholinergic activation.•Pilocarpine acts on central M1 and M2 receptors to facilitate sodium intake.•NaCl intake after muscimol injection into the parabrachial nucleus depends on central M1 receptors. Central cholinergic activation stimulates water intake, but also NaCl intake when the inhibitory mechanisms are blocked with injections of moxonidine (α2 adrenergic/imidazoline agonist) into the lateral parabrachial nucleus (LPBN). In the present study, we investigated the involvement of central M1 and M2 muscarinic receptors on NaCl intake induced by pilocarpine (non-selective muscarinic agonist) intraperitoneally combined with moxonidine into the LPBN or by muscimol (GABAA agonist) into the LPBN. Male Holtzman rats with stainless steel cannulas implanted bilaterally in the LPBN and in the lateral ventricle were used. Pirenzepine (M1 muscarinic antagonist, 1 nmol/1 μl) or methoctramine (M2 muscarinic antagonist, 50 nmol/1 μL) injected intracerebroventricularly (i.c.v.) reduced 0.3 M NaCl and water intake in rats treated with pilocarpine (0.1 mg/100 g of body weight) injected intraperitoneally combined with moxonidine (0.5 nmol/0.2 μL) into the LPBN. In rats treated with muscimol (0.5 nmol/0.2 μL) into the LPBN, methoctramine i.c.v. also reduced 0.3 M NaCl and water intake, however, pirenzepine produced no effect. The results suggest that M1 and M2 muscarinic receptors activate central pathways involved in the control of water and sodium intake that are under the influence of the LPBN inhibitory mechanisms.