Fluid Balance and Baroreflex response: neuromodulators, neural circuits and sex chromosome complement influences.

GODINO, A.; CAEIRO, X.; CAMBIASSO, MJ; VIVAS, L

Revista de Farmacologia de Chile

Sociedad de Farmacologia de Chile

Lugar: Santiago; Año: 2015 vol. 8 p. 35 - 51

Changes in body water/sodium balance are tightly controlled by the CNS to avoid an abnormal cardiovascular function and develop of pathological states. This process of sensory integration takes place in different nuclei, with diverse phenotype and at different levels of the CNS. Our aim was to study the specific neurochemical groups, their roles, their connections and the associated endocrine responses during body sodium depletion or sodium overload conditions. For this purpose we combined the immunohistochemical detection of different neurotransmitters, a retrograde transported dye and a marker of neural activity. We also determined the involvement of sex chromosome complement (SCC) on both bradycardic baroreflex response and on brain activity in a sodium depletion model. Our results demonstrated that the activity of serotonergic and oxytocinergic neurons significantly increase during a blood volume expansion suggesting their involvement in the homeostatic regulatory response. We also observed a tonic activity of serotonergic neurons of dorsal raphe nucleus (DRN) during the first hours after sodium depletion, then the activity decreased 24 h after a sodium depletion and increased after body sodium reestablishment, independently of the sodium concentration of the solution consumed, suggesting that this system is involved in the inhibition of sodium appetite under conditions of satiety. In contrast, the paraventricular and supraoptic oxytocinergic neurons were activated, and the oxytocin plasma levels increased only after hypertonic NaCl intake, in both depleted and non-depleted animals, suggesting that this system is involved in the processing of hyperosmotic signals. Our hodological results provide insight into how the different areas such as DRN and lateral parabrachial nucleus, form a neural network that regulates body fluid balance, showing the main integratory nuclei involved in the satiety phase of sodium appetite and consequently in the regulation of an extracellular volume. Finally we also demonstrated that that SCC influences bradycardic baroreflex response and modulates brain activity in nuclei closely involved in the regulatory response to RAS stimulation.