Electrophysiological Evidence for Functional Astrocytic P2X3 Receptors in the Mouse Trigeminal Caudal Nucleus.

Recently, we reported that astrocytes in the trigeminal caudal nucleus (Vc) of the brain stem express a purinergic receptor P2X3, which is involved in the craniofacial pathologic pain. Although we observed protein expression of P2X3 receptors (P2X3 Rs) in the astrocyte of the Vc, it is still unclear that astrocyte has functional P2X3Rs in Vc. To address this issue, we recorded asrtocytic P2X3Rs by using whole cell voltage-clamp recording in the Vc of the GFAP-GFP mice, which was used as a guide to astrocytes with green fluorescence. While measuring voltage ramp-induced astrocytic membrane current, we found the amplitude of the current was increased when we applied P2-purinoreceptor agonist, α,β-meATP. This increase was blocked by co-application of A317491, P2X3R antagonist. These results demonstrate that astrocytes in the Vc express functional P2X3Rs, which might be critical in craniofacial pathologic pain.