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Glial Cells Are Involved in ANG-II-Induced Vasopressin Release and Sodium Intake in Awake Rats.

Frontiers in physiology (2018-05-17)
Atalia F L Flôr, José L de Brito Alves, Maria S França-Silva, Camille M Balarini, Lucila L K Elias, Silvia G Ruginsk, José Antunes-Rodrigues, Valdir A Braga, Josiane C Cruz
ABSTRACT

It is known that circulating angiotensin II (ANG-II) acts on the circumventricular organs (CVOs), which partially lack a normal blood-brain barrier, to stimulate pressor responses, vasopressin (AVP), and oxytocin (OT) secretion, as well as sodium and water intake. Although ANG-II type 1 receptors (AT1R) are expressed in neurons and astrocytes, the involvement of CVOs glial cells in the neuroendocrine, cardiovascular and behavioral responses induced by central ANG II remains to be further elucidated. To address this question, we performed a set of experiments combining in vitro studies in primary hypothalamic astrocyte cells (HACc) and in vivo intracerebroventricular (icv) microinjections into the lateral ventricle of awake rats. Our results showed that ANG-II decreased glutamate uptake in HACc. In addition, in vivo studies showed that fluorocitrate (FCt), a reversible glial inhibitor, increased OT secretion and mean arterial pressure (MAP) and decreased breathing at rest. Furthermore, previous FCt decreased AVP secretion and sodium intake induced by central ANG-II. Together, our findings support that CVOs glial cells are important in mediating neuroendocrine and cardiorespiratory functions, as well as central ANG-II-induced AVP release and salt-intake behavior in awake rats. In the light of our in vitro studies, we propose that these mechanisms are, at least in part, by ANG-II-induced astrocyte mediate reduction in glutamate extracellular clearance.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Monoclonal Anti-SLC1A2 antibody produced in mouse, clone 4G8, purified immunoglobulin, buffered aqueous solution
Sigma-Aldrich
Anti-Glial Fibrillary Acidic Protein antibody produced in rabbit, IgG fraction of antiserum, buffered aqueous solution