P2X₃, but not P2X₁, receptors mediate ATP-activated current in neurons innervating tooth-pulp

Abstract

We developed a method that allows us to label nociceptive neurons innervating tooth-pulp in rat trigeminal ganglion neurons using a retrograde fluorescence-tracing method, to record ATP-activated current in freshly isolated fluorescence-labeled neurons and to conduct single cell immunohistochemical staining for P2X₁ and P2X₃ subunits in the same neuron. Three types of ATP-activated current in these neurons (F, I and S) were recorded. The cells exhibiting the type F current mainly showed positive staining for P2X₃, but negative staining for P2X₁. The results provide direct and convincing evidence at the level of single native nociceptive neurons for correlation of the characteristics of ATP-activated currents with their composition of P2X₁ and P2X₃ subunits and cell size. The results also suggest that the P2X₃, but not P2X₁, is the main subunit that mediates the fast ATP-activated current in nociceptive neurons.

Keywords

P2X / phenotype / genotype / tooth-pulp / trigeminal ganglion / retrograde fluorescence-tracing / immunohistochemistry / nociceptor

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