?Oxytocinergic System Involvement During States Of Body Hypertonicity?.

PITRA MS.; VIVAS L.; GODINO A.

Encuentro; IIRCN First Joint Meeting of the Argentine Society for Neuroscience (SAN) and the Argentine Workshop in Neurosciences (TAN).; 2010

Our previous results indicate that both isotonic and hypertonic (HI) volume expansion (VE) increase the plasma oxytocin (OT) levels and the activity of hypothalamic OT neurons in order to increase renal excretion and re-establish extracellular volume. We have shown, recently, activation of the OT system after hypertonic NaCl intake; however this intake also produced a small extracellular VE.  These results provide further support to the idea that the presence of both stimuli simultaneously, VE and HI, are able to increase the OT system activity. Our aim was to study the OT system involvement during a hypertonic sodium overload (HSO) that doesn?t induce any extracellular VE. We analyzed the number of brain Fos-OT-immunoreactive neurons, the renal, endocrine and behavioural responses during a s.c. HSO, without changes in the extracellular volume. Our results indicate that HSO significantly increased the OT plasma concentration and the activity of the OT supraoptic neurons. We also confirm that the HSO increased significantly the water intake and the renal excretion. We conclude that a body hypertonic state itself without involving VE can increase the activity of OT neurons and the plasma OT release, possibly to modulate sodium/water intake/excretion and avoid an extracellular VE.