Enhancement of meal-associated hypertonic NaCl intake by moxonidine into the lateral parabrachial nucleus
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Data
2007-11-02
Autores
Andrade, Carina A.F. [UNESP]
De Luca Jr., Laurival A. [UNESP]
Colombari, Débora S.A. [UNESP]
Menani, José Vanderlei [UNESP]
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Resumo
α2-Adrenoceptor activation with moxonidine (α2-adrenergic/imidazoline receptor agonist) into the lateral parabrachial nucleus (LPBN) enhances angiotensin II/hypovolaemia-induced sodium intake and drives cell dehydrated rats to ingest hypertonic sodium solution besides water. Angiotensin II and osmotic signals are suggested to stimulate meal-induced water intake. Therefore, in the present study we investigated the effects of bilateral injections of moxonidine into the LPBN on food deprivation-induced food intake and on meal-associated water and 0.3 M NaCl intake. Male Holtzman rats with cannulas implanted bilaterally into the LPBN were submitted to 14 or 24 h of food deprivation with water and 0.3 M NaCl available (n = 6-14). Bilateral injections of moxonidine (0.5 nmol/0.2 μl) into the LPBN increased meal-associated 0.3 M NaCl intake (11.4 ± 3.0 ml/120 min versus vehicle: 2.2 ± 0.9 ml/120 min), without changing food intake (11.1 ± 1.2 g/120 min versus vehicle: 11.2 ± 0.9 g/120 min) or water intake (10.2 ± 1.5 ml/120 min versus vehicle: 10.4 ± 1.2 ml/120 min) by 24 h food deprived rats. When no food was available during the test, moxonidine (0.5 nmol) into the LPBN of 24 h food-deprived rats produced no change in 0.3 M NaCl intake (1.0 ± 0.6 ml/120 min versus vehicle: 1.8 ± 1.1 ml/120 min), nor in water intake (0.2 ± 0.1 ml/120 min versus vehicle: 0.6 ± 0.3 ml/120 min). The results suggest that signals generated during a meal, like dehydration, for example, not hunger, induce hypertonic NaCl intake when moxonidine is acting in the LPBN. Thus, activation of LPBN inhibitory mechanisms seems necessary to restrain sodium intake during a meal. © 2007 Elsevier B.V. All rights reserved.
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Palavras-chave
α2-Adrenergic receptors, Food intake, Sodium appetite, Thirst, angiotensin II, hypertonic solution, moxonidine, sodium chloride, water, animal experiment, animal model, animal tissue, cannulation, controlled study, dehydration, fluid intake, food deprivation, food intake, hyperosmotic stress, male, nonhuman, osmolarity, parabrachial nucleus, priority journal, rat, Analysis of Variance, Animals, Antihypertensive Agents, Behavior, Animal, Drinking, Drinking Behavior, Eating, Food Deprivation, Imidazoles, Male, Pons, Rats, Saline Solution, Hypertonic, Time Factors
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Behavioural Brain Research, v. 183, n. 2, p. 156-160, 2007.