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Advanced Neurology Brain AT -R and kidney crosstalk
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In the sham group, free water clearance did not The PVN physiological relevance appears to be lower
show statistical differences in response to diet or Los than SON since the neuronal activity was not affected by
administration (diet factor F (1,27) = 2.83, p = NS; treatment the hypersodic diet. It is important to highlight the great
factor F (1,27) = 0.07, p = NS; and interaction F (1,27) = 0.19, cell heterogeneity in PVN compared to SON. In this sense,
p = NS) (Table 3). Similar results were observed in the PVN is a highly complex nucleus when CRH, GNRH, AVP,
RDN group (diet factor F (1,20) = 0.16, p = NS; treatment and oxytocin synthesis take place and receive inputs from
factor F (1,20) = 1.48, p = NS; and interaction F (1,20) = 4.12, several brain regions [42,43] . Meanwhile, SON presents less
p = NS) (Table 3). complexity when the neurons synthesizing oxytocin and
AVP are bigger and easily identified .
[44]
4. Discussion
The SNS activity interruption induced a marked
The main finding of this study is the ANG II’s main decrease in SFO neuronal activity, indicating a basal
role, through AT -R, in the complex interaction system stimulatory tone in this nucleus that is not observed in
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between CNS and SNS over renal function control. There OVLT. Nevertheless, in both nuclei, the sodium overload
is considerable evidence supporting that RAS components alters the neuronal activation under renal denervation
are present in the tissue and plasma, and they can act conditions, evidencing a differential regulatory role from
independently or linked through regulatory pathways [35-38] . SNS on the neural components of these nuclei . SFO
[12]
The SNS involvement in the renal sodium equilibrium and OVLT exert key functions in the extracellular sodium
under normal and pathological conditions is modulated concentrations since they are related to sodium appetite
by ANG II actions over AVP. Moreover, it has been shown and are sensitive to ANG II [12,14,34,45] .
that Los reduces RAS and SNS activity. Renal denervation 4.2. Renal effects: Water and sodium balance
is a delicate and specific surgical approach. It is very useful
as it can recreate conditions similar to renal transplanted The variations in sodium excretion affect the extracellular
individuals. volume activating complex response mechanisms that
re-establish the hydrosaline homeostasis.
In the present study, we perform the experiments
6 days after renal denervation, based on the fact that It is known that AVP and oxytocin play a key role
[46]
in this period, the anatomical-physiological renal in osmoregulation through natriuresis and diuresis .
nerve interruption persists, allowing the renal function The anatomic-physiological evidence shows that the
evaluation without sympathetic influence [27-30] . The applied sympathetic nerves regulate changes in the urinary sodium
experimental protocol using renal denervation and central and water excretion through the tubular reabsorption at
Los administration evidenced the ANG II role at the the nephron level. AVP targets the collector tubules, and its
[9]
brain level, independently from its functions through SNS release is under brain ANG II regulation through AT -R .
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modulation. In this sense, renal denervation allows us to unmask the
central actions of these receptors and their interaction with
4.1. Hypersodic diet induced-neuronal activation SNS in renal sodium regulation.
Evidence shows that brain ANG II -through AT -R- is Our results show that the increase in water intake
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involved in blood pressure control, SNS stimulation, AVP induced by a hypersodic diet is mediated by brain AT -R
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release, and water and sodium intake . The presence of since this increase was prevented by Los administration.
[36]
AT -R in PVN, SON, OVLT, and SFO brain areas involved Moreover, this regulation involves the SNS considering
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in arterial blood pressure control and hydroelectrolytic that renal denervation was able to avoid the increase
homeostasis has been described [36,39] . in water intake induced by the hypersodic diet, and Los
[47]
The marked increase in the number of c-Fos-IR administration re-established this response . A similar
neurons in the SON from intact animals was blunted phenomenon was observed in the urinary volume increase
by Los administration, suggesting that AT -R mediates induced by hypersodic diet in intact animals. This increase
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the neuronal activation induced by a moderated was abolished by renal denervation and re-established by
hypersodic diet . The renal denervation avoided the the AT -R blockade. These results not only confirm the
[40]
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described increase in neuronal activation induced by the existence of the SNS-brain ANG II circuit loop but also its
hypersodic diet, evidencing the close interaction between critical regulatory function.
SON vasopressinergic neurons and SNS activity. These Regarding daily food intake, we did not observe differences
constitute the essential circuit loop SON-SNS-kidney, the between diets, meaning sodium did not modify palatability.
principal components involved in the sodium overload In the same way, renal denervation or Los administration did
neuroregulation in this experimental paradigm [12,41] . not affect food intake. However, water intake was increased

Volume 2 Issue 2 (2023) 10 https://doi.org/10.36922/an.393