Cerebellar astrocytes coexpress different purinoceptors: Cross-talk between several transduction mechanisms

Abstract

We characterized the purinergic receptors present in individual type-1 astrocytes from rat cerebellum by using single cell microfluorimetry with fura-2. We found that individual astrocytes coexpressed several P2Y purinoceptors coupled to phospholipase C activation through different G proteins. P2Y1 and P2Y2 or P2Y4 purinoceptors were responsible for the ATP, 2MeSATP, and UTP calcium responses observed in all tested cell. A subpopulation of astrocytes also coexpressed a specific pyrimidine receptor, which was responsible for UDP calcium responses recorded only from a subpopulation of astrocytes. Type-1 astrocytes also present A2B adenosine receptors positively coupled to adenylate cyclase. There was a positive interaction between A2B adenosine receptors and P2Y1 or P2Y2 or P2Y4 purinoceptors expressed in the same astrocyte. We also found that the stimulation of astrocytes with nanomolar concentrations of Ap5A produced the activation of extracellular signal regulated kinases (ERK), which could be responsible for the potentiation of ATP calcium responses elicited by the dinucleotide.