Purinergic receptors activating rapid intracellular Ca~(2+) increases in microglia

摘要

We provide both molecular and pharmacological evidence that the metabotropic, purinergic, P2Y_6, P2Y_(12) and P2Y_(13) receptors and the ionotropic P2X4 receptor contribute strongly to the rapid calcium response caused by ATP and its analogues in mouse microglia. Real-time PCR demonstrates that the most prevalent P2 receptor in microglia is P2Y6 followed, in order, by P2X_4, P2Y_(12), and P2X_7 = P2Y_(13). Only very small quantities of mRNA for P2Y1, P2Y2, P2Y_4, P2Y_(14), P2X_3 and P2X_5 were found. Dose-response curves of the rapid calcium response gave a potency order of: 2MeSADP>ADP=UDP=IDP=UTP>ATP>BzATP, whereas A2P_4 had little effect. Pertussis toxin partially blocked responses to 2MeSADP, ADP and UDP. The P2X_4 antagonist suramin, but not PPADS, significantly blocked responses to ATP. These data indicate that P2Y_6, P2Y_(12), P2Y_(13) and P2X receptors mediate much of the rapid calcium responses and shape changes in microglia to low concentrations of ATP, presumably at least partly because ATP is rapidly hydrolyzed to ADP.