Purinergic signalling in neuron-glia interactions at the PVN level during osmotic challenges

• Grant number: 18/11203-3
• Support Opportunities: Scholarships abroad - Research Internship - Doctorate
• Start date: October 01, 2018
• End date: September 30, 2019
• Field of knowledge: Biological Sciences - Physiology - Physiology of Organs and Systems
• Principal Investigator: Vagner Roberto Antunes
• Grantee: Renato Willian Martins Sá
• Supervisor: Alexander V Gourine
• Host Institution: Instituto de Ciências Biomédicas (ICB). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Institution abroad: University College London (UCL), England
• Associated to the scholarship: 16/03359-8 - Role of glia and ectonucleotidases in the purinergic signaling of the paraventricular nucleus of the hypothalamus in salt-induced hypertension, BP.DR

Abstract

Preliminary data from my PhD project have shown that salt-sensitive neurogenic hypertension elicits an increased in the mRNA level of the ectonucleotidase triphosphate diphosphohydrolase 3 (E-NTPD3) in the hypothalamic paraventricular nucleus (PVN). This enzyme hydrolyses ATP to ADP and ADP to AMP, and increase the concentration of a substrate of ecto-5'-nucleotidase (AMP) to produce adenosine. These data suggest that the concentration of ATP and adenosine in the PVN may be affected by a hyperosmotic stimulus, a consequence of the salt-loading condition. However, to confirm our results and for a better interpretation of them it is fundamental to determine whether the enzymatic activity of ectonucleotidases and the concentration of ATP and adenosine in the PVN are really affected by a hyperosmotic stimulus. Moreover, since astrocytes constitute as a major source of ATP within the CNS, and this process can be evoked by physiologically relevant signals it will be important to assess whether astrocytes are key participants in osmotically-driven changes in the ATP/adenosine balance within PVN. The aim of this proposal is to investigate the role of purinergic signalling of in neuron-astrocytes interaction and ectonucleotidases within the PVN in control of ATP availability during hyperosmotic stimulus. Acute brain slices containing PVN will be prepared and specific biosensors of ATP and adenosine will be placed in the PVN surfaces to evaluate the release of these purines before and after bath application of a hypertonic solution (mannitol 1%, +55 mOsm). Topical application of an ectonucleotidase inhibitor ARL 67156 and an agonist for the G protein-coupled PAR-1 receptor will be performed to determine the role of ectonucleotidases and astrocytes in osmotically-driven changes in the ATP/adenosine balance within PVN.