INIMEC - CONICET   05467
INSTITUTO DE INVESTIGACION MEDICA MERCEDES Y MARTIN FERREYRA
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Participation of serotonergic and oxytocinergic systems on sodium intake regulation.
Autor/es:
GODINO,A.; ANTUNES-RODRIGUES, J., DE LUCA, LA, VIVAS, L.
Lugar:
Buenos Aires
Reunión:
Congreso; XXII Latin-American and First Ibero-American Congress of Physiological Sciences (IBERO-ALACF); 2006
Institución organizadora:
Asoc. Latinoamericana de Cs. Fisiologicas, Soc. Argentina de Fisiologia
Resumen:
Participation of serotonergic and oxytocinergic systems on sodium intake regulation. ¹Godino, A.;  ²Antunes-Rodrigues, J.; 3De Luca, LA Jr, and ¹Vivas, L. ¹INIMEC, Cba., Argentine. ²Physiology Dept.,USP, Physiology and Pathology Depts., UNESP Brazil.   Our recent studies demonstrated the inhibitory participation of the serotonergic (5HT) and oxytocinergic (OT) systems on sodium appetite induced by peritoneal dialysis (PD). In this model the activity of 5HT neurons increased after 2% NaCl intake and decreased when the animals were sodium depleted; however, the activity of the OT neurons appeared only after 2% NaCl intake. This effect would not be specifically associated with an inhibitory influence of oxytocin on sodium appetite; maybe it would be a consequence of the OT system stimulation by means of hypernatremic signals. The aim of the present work was to discriminate whether the activation of the 5HT and OT neurons observed in our paradigm is the result of sodium satiation process or the stimulation induced by hypertonic sodium ingestion. Adult male Albino rats were sodium depleted by PD. Twenty-four hours after PD or Control peritoneal dialysis (CD), the groups had access to 2% NaCl (CD 2% and PD 2% groups) or 0.9% NaCl (CD 0.9% and  PD 0.9% groups) drinking test. The animals were decapitated and bled after drinking test and OT plasma levels were measured by RIA. Separated group of animals were perfused for immunohistochemical detection of Fos, Fos-5HT and Fos-OT, 90 minutes after drinking test. Sodium intake induced by PD significantly increased the number of Fos-5HT cells (P<0.001), independent of NaCl  concentration of fluid consumed. In contrast, the number of Fos-OT neurons, increased after 2% NaCl intake (P<0.05) but did not change after 0.9% NaCl ingestion. The OT plasma levels significantly increased in PD 2% groups compared to others showing a synergic effect of both factors (P<0.05). In summary, 5HT neurons were stimulated after body sodium status reestablishment consistent with the idea that this system is activated under conditions of satiety. In relation to the OT system both, the OT neural activity and the OT plasma levels were increased by the entering of hypertonic NaCl solution during sodium consumption, suggesting that this system is involved  in the processing of hyperosmotic signals. Supported by CONICET, ANPCyT and CNPq.