Under normal and pathological conditions, brain cells release nucleotides that regulate a wide range of cellular responses due to activation of P2 nucleotide receptors. In this study, the effect of extracellular nucleotides on IFNc-induced NO release in murine BV-2 microglial cells was investigated. BV-2 cells expressed mRNA for metabotropic P2Y and ionotropic P2X receptors. Among the P2 receptor agonists tested, ATP, ADP, 2¢,3¢-O-(4-benzoylbenzoyl)-ATP (BzATP), and 2-methylthio-ATP (2-MeSATP), but not UTP, enhanced IFNc-induced iNOS expression and NO production, suggesting that the uridine nucleotide receptors P2Y 2 and P2Y 6 are not involved in this response. U0126, an antagonist for MEK1/2, a kinase that phosphorylates the extracellular signal-regulated kinases ERK1/2, decreased IFNc-induced NO production. BzATP, a potent P2X 7 receptor agonist, was more effective than ATP, ADP, or 2-MeSATP at enhancing IFNc-induced ERK1/2 phosphorylation. Consistent with activation of the P2X 7 receptor, periodate-oxidized ATP, a P2X 7 receptor antagonist, and suramin, a non-specific P2 receptor antagonist, inhibited the effect of ATP or BzATP on IFNc-induced NO production, whereas pyridoxal-phosphate-6-azophenyl-2¢,4¢-disulfonic acid (PPADS), an antagonist of several P2X receptor subtypes, was ineffective. These results suggest that activation of P2X 7 receptors may contribute to inflammatory responses in microglial cells seen in neurodegenerative diseases.
