Serotonergic system involvement during states of body hypertonicity

PITRA S, VIVAS L AND GODINO A

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

SAN

Serotonergic system involvement during states of body hypertonicity Pitra S, Vivas L and Godino A. INIMEC-CONICET. Facultad de Ciencias Exactas, Físicas y Naturales. UNC. Our previous studies demonstrated the serotonergic system participation in the inhibition of sodium appetite induced by peritoneal dialysis. In this model, Fos expression, used as a marker of neuronal activity, decreases when animals are sodium depleted and increases when animals are in the process of restoring sodium balance through ingestion, in serotonergic dorsal raphe nucleus (DRN) cells. Pharmacological and lesion studies have also demonstrated the contribution of 5HT system in renal sodium excretion. Taken together, the evidence suggests that body sodium levels modulate the activity of the 5HT-DRN system. Our aim was to study the 5HT system involvement during a hypertonic sodium overload (HSO). The HSO was performed by a sc injection of 0.6 ml/100g bw of 2M NaCl solution. Ninety minutes later the rats were subjected to immunohistochemical detection of Fos and 5HT. Our results indicate that the HSO significantly increased 5HT-DRN cells activity and also induced a significant increase in Fos expression along brain stem, lamina terminalis and central extended amygdala nuclei. In summary, a HSO itself can increase the activity of 5HT-DRN cells together with specific brain cell groups, possibly to modulate sodium balance and avoid an extracellular volume expansion.