Purinergic P2Y1 Receptors Control Rapid Expression of Plasma Membrane Processes in Hippocampal Astrocytes.
Astrocytes regulate neuronal activity and blood brain barrier through tiny plasma membrane branches or astrocytic processes (APs) making contact with synapses and brain vessels. Several transmitters released by astrocytes and exerting their action on several receptor classes expressed by astrocytes themselves influence their physiology. Here we found that APs are dynamically modulated by purines. In live imaging experiments carried out in rat hippocampal astrocytes, Gq-coupled P2Y1 receptor blockade with the selective antagonist MRS2179 (1 μM) or inhibition of its effector phospholipase C using U73122 (3 μM) produced APs retraction, while stimulation of the same receptor with the selective agonist 2MeSADP (100 μM) increased their number. Since astrocytes, among other transmitters, release ATP by several mechanisms including connexin hemichannels, we used the connexin hemichannel inhibitor carbenoxolone (100 μM) and APs retraction was observed. In our system we then measured expression or function of channels important for modulation of volume transmission and K+ buffering, aquaporin-4, and K+ inward rectifying (Kir) channels, respectively. Aquaporin-4 expression level did not change whereas, in whole-cell patch-clamp recordings performed to measure Kir current, we observed an increase in K+ current in all conditions where APs number was reduced. These data are supporting the idea of a dynamic modulation of astrocytic processes by purinergic signal, strengthening the role of purines in brain homeostasis.
Department of Biomedical and Biotechnological Sciences, Section of Pharmacology, University of Catania, Via Santa Sofia, 64, 95125, Catania, Italy. chisarim@gmail.com.
Mariangela
0000-0002-2984-0375
M
Chisari
Department of Biomedical and Biotechnological Sciences, Section of Pharmacology, University of Catania, Via Santa Sofia, 64, 95125, Catania, Italy.
Angela
A
Scuderi
Department of Biomedical and Biotechnological Sciences, Section of Physiology, University of Catania, Catania, Italy.
Lucia
L
Ciranna
Department of Biomedical and Biotechnological Sciences, Section of Physiology, University of Catania, Catania, Italy.
Guido Li
GL
Volsi
Department of Biomedical and Biotechnological Sciences, Section of Physiology, University of Catania, Catania, Italy.
Flora
F
Licata
Department of Biomedical and Biotechnological Sciences, Section of Pharmacology, University of Catania, Via Santa Sofia, 64, 95125, Catania, Italy.
Maria Angela
MA
Sortino
D000818:Animals; D051401:Aquaporin 4 / Q000378:metabolism; D001253:Astrocytes / Q000378:metabolism*; D020013:Calcium Signaling; D002462:Cell Membrane / Q000378:metabolism*; D002478:Cells, Cultured; D017630:Connexins / Q000378:metabolism; D051676:G Protein-Coupled Inwardly-Rectifying Potassium Channels / Q000378:metabolism; D006624:Hippocampus / Q000378:metabolism*; D017207:Rats, Sprague-Dawley; D058472:Receptors, Purinergic P2Y1 / Q000378:metabolism*; D010738:Type C Phospholipases / Q000037:antagonists & inhibitors / Q000378:metabolism
D051401:Aquaporin 4; D017630:Connexins; D051676:G Protein-Coupled Inwardly-Rectifying Potassium Channels; D058472:Receptors, Purinergic P2Y1; D010738:Type C Phospholipases
ATP; Aquaporin-4; Astrocytic processes; Glia-neuron crosstalk; Kir channels