Electrophysiological Evidence for Functional Astrocytic P2X(3) 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 P2X(3), which is involved in the craniofacial pathologic pain. Although we observed protein expression of P2X(3) receptors (P2X(3) Rs) in the astrocyte of the Vc, it is still unclear that astrocyte has functional P2X(3)Rs in Vc. To address this issue, we recorded asrtocytic P2X(3)Rs 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, P2X(3)R antagonist. These results demonstrate that astrocytes in the Vc express functional P2X(3)Rs, which might be critical in craniofacial pathologic pain.