title: Would right atrial stretch inhibit sodium intake following GABAA receptor activation in the lateral parabrachial nucleus?
abstract: The knowledge of the mechanisms underlying circulating volume control may be achieved by stretching a balloon placed at the junction of the superior vena cava-right atrial junction (SVC-RAJ). We investigated whether the inflation of a balloon at the SVC-RAJ inhibits the intake of 0.3M NaCl induced by GABAA receptor activation in the lateral parabrachial nucleus (LPBN) in euhydrated and satiated rats. Male Wistar rats (280-300 g) with bilateral stainless steel LPBN cannulae and balloons implanted at the SVC-RAJ were used. Bilateral injections of the GABAA receptor agonist muscimol (0.5 ηmol/0.2l) in the LPBN with deflated balloons increased intake of 0.3M NaCl (30.1 ± 3.9 vs. saline: 2.2 ± 0.7)ml/210 min, n=8) and water (17.7 ± 1.9 vs. saline: 2.9 ± 0.5 ml/210 min). Conversely, 0.3M NaCl (27.8 ± 2.1 ml/210 min) and water (22.8 ± 2.3 ml/210 min) intake were not affected in rats with inflated balloons at the SVC-RAJ. The results show that sodium and water intake induced by muscimol injected into the LPBN was not affected by balloon inflation at the SVC-RAJ. We suggest that the blockade of LPBN neuronal activity with muscimol injections impairs inhibitory mechanisms activated by signals from cardiopulmonary volume receptors determined by balloon inflation.
authors: Department of Physiology, Institute of Bioscience, São Paulo State University (UNESP), 18618-000 Botucatu, SP, Brazil.
authors: Caroline Gusson
authors: CG
authors: Shimoura
authors: Silas Pereira
authors: SP
authors: Barbosa
authors: Jose Vanderlei
authors: JV
authors: Menani
authors: Juliana Irani Fratucci
authors: JI
authors: De Gobbi
mesh_terms: D000818:Animals; D002404:Catheterization; D004326:Drinking; D058785:GABA-A Receptor Agonists / Q000494:pharmacology*; D006321:Heart / Q000187:drug effects / Q000503:physiopathology*; D006325:Heart Atria / Q000503:physiopathology; D008297:Male; D009118:Muscimol / Q000494:pharmacology*; D011149:Pons / Q000378:metabolism*; D017208:Rats, Wistar; D011963:Receptors, GABA-A / Q000378:metabolism*; D012965:Sodium Chloride / Q000008:administration & dosage / Q000378:metabolism*; D014683:Vena Cava, Superior / Q000503:physiopathology
chemical_list: D058785:GABA-A Receptor Agonists; D011963:Receptors, GABA-A; D009118:Muscimol; D012965:Sodium Chloride
keywords: Cardiopulmonary volume receptors; Circulating volume; GABA(A); Lateral parabrachial nucleus; Right atrial stretch; Sodium intake