Localization of ATP-gated P2X receptor immunoreactivity in rat sensory and sympathetic ganglia.

The distribution of P2X1, P2X2, P2X3, P2X4, P2X5 and P2X6 receptors, a family of ATP-gated cation channels, in rat trigeminal, dorsal root, nodose, superior cervical, and coeliac ganglia was studied immunohistochemically. It was found that polyclonal antibodies for the six P2X receptor subtypes could label over 90% of neurones in these ganglia to different intensities. There was also considerable variation in intensity of immunoreactivity in individual neurones within each ganglion. In dorsal root and trigeminal ganglia expression of the P2X3 receptor was much higher than for the other five subtypes. P2X3 immunoreactivity was much more intense in the small-diameter neurones than in the large-diameter neurones. In nodose ganglion, both P2X2 and P2X3 antibodies labelled the neurones intensely. In sympathetic superior cervical and coeliac ganglia, immunoreactivity to five P2X receptor subtypes were detected (exception, P2X5), with P2X2, P2X4 and P2X6 showing higher intensity. Low level expression of P2X3 receptor in sympathetic ganglia indicates that this receptor subtype is not limited to the sensory ganglia where it was highly expressed. The results have demonstrated that both sensory and sympathetic ganglia express a variety of P2X receptor subtypes and that different subtypes are expressed to different levels and by different subpopulations of neurones.