Signaling and Ca Wave Propagation in Dorsal Spinal Cord Astrocytes

ATP is known to act as an extracellular messenger mediating the propagation of Ca waves in astrocyte networks. ATP mediates Ca waves by activating P2Y purinoceptors, which mobilize intracellular Ca in astrocytes. A number of P2Y purinoceptor subtypes have been discovered, but it is not known which P2Y subtypes participate in transmitting astrocyte Ca waves. Here, we show that ATP analogs that are selective agonists for the P2Y1 subtype of purinoceptor caused release of intracellular Ca in astrocytes from the dorsal spinal cord. The Ca responses were blocked by adenosine-39phospho-59-phosphosulfate, an antagonist known to selectively inhibit P2Y1 but not other P2Y purinoceptor subtypes. Also, we show that P2Y1 mRNA is expressed in dorsal spinal cord astrocytes. Furthermore, expression of P2Y1 in an astrocytoma cell line lacking endogenous purinoceptors was sufficient to permit propagation of intercellular Ca waves. Finally, Ca wave propagation in dorsal spinal cord astrocytes was suppressed by pharmacologically blocking P2Y1 purinoceptors. Together, these results indicate that dorsal spinal astrocytes express functional P2Y1 purinoceptors, which participate in the transmission of Ca 21 waves. Ca 21 waves in astrocytes have been implicated as a major signaling pathway coordinating glial and neuronal activity; therefore, P2Y1 purinoceptors may represent an important link in cell–cell signaling in the CNS.