Gradual changes in body sodium status induce a specific pattern of behavioural, renal and brain activity.

BEAS C, MACCHIONE AF, VIVAS L

Congreso; XXVI Congreso Anual de la Sociedad Argentina de Investigación en Neurociencia; 2011

We analyzed the effect of gradual changes in body Na status induced by iv infusions of hypotonic (0.075M) and mild(0.3M)/high(1.5M) hypertonic Na solutions on drinking, renal and brain activity responses. Male rats were iv infused with either of the 3 solutions or saline(0.15M) as a control (0.15ml/min/20min). For behavioural and urinary measurements, rats had access to water during the infusion period and 2h after. For immunohystochemical studies other group of rats was infused without access to water and brains were collected 60min after the 20min inf. Our results indicate that both 0.3M and 1.5M groups had a gradual increase in renal Na-excretion but only in the 1.5M group, thirst was elicit. Consistently, the telencephalic circumventricular organs (CVOs) were activated in 1.5M group while the supraoptic vasopressinergic/oxitocinergic (AVP/OT) cells were gradually activated in both, 0.3M and 1.5M groups. The 0.075M group had a different K-renal-excretion suggesting the existence of aldosterone-mediated cell-volume regulation. Our data reveals that a gradual increase in body Na status first triggers the renal response and the hypothalamic AVP/OT cells activation without any drinking response. A higher level of Na overload elicits thirst and the activation of telencephalic CVOs. Supported by CONICET, SECyT and ANPCyT.