Evidence for P2Y1, P2Y2, P2Y6 and atypical UTP-sensitive receptors coupled to rises in intracellular calcium in mouse cultured superior cervical ganglion neurons and glia

1 P2Y receptors are expressed in the nervous system and are involved in calcium signalling in neurons and glia. In the superior cervical ganglion (SCG), RT-PCR analysis indicated the presence of P2Y(1,2&6) receptors. Rises in intracellular calcium in response to P2Y receptor stimulation were determined from adult mouse cultured SCG neurons and glia. 2 ADP evoked suramin (100 microM)- and pyridoxalphosphate-6-azophenyl-2',4'-disulphonic acid (PPADS, 30 microM)-sensitive rises in intracellular calcium in approximately 80% of SCG neurons (EC50 approximately 20 microM). ADP-evoked responses were abolished in neurons from P2Y1 receptor-deficient mice (responses to UTP were unaffected). 3 The pyrimidines UTP (EC50 approximately 85 microM) and UDP (EC50>90 microM) evoked PPADS- and suramin-sensitive responses in approximately 70 and approximately 20% of SCG neurons, respectively. 4 In SCG glial cells, ADP (EC50 approximately 30 microM) evoked calcium responses in approximately 50% of glia. These were suramin and PPADS sensitive and essentially abolished in SCG glial cells cultured from adult P2Y1 receptor-deficient mice. 5 UTP (EC50 approximately 25 microM) and UDP (EC50>200 microM) evoked suramin- and pyridoxalphosphate-6-azophenyl-2',5'-disulphonate-sensitive rises in calcium in approximately 60 and 20% SCG glial cells, respectively. 6 These results indicate the presence of several P2Y receptors coupled to an increase in intracellular calcium in the SCG: ADP-sensitive P2Y1 receptors and UDP-sensitive P2Y6 receptors in SCG neurons and glial cells, a novel UTP-sensitive P2Y receptor in SCG neurons and UTP- and ATP-sensitive P2Y2 receptors in SCG glia.