Anales RANF

P.43 INVOLVEMENT OF P2X7RS IN EXCITATORY NEUROTRANSMISSION IN THE MOUSE DENTATE GYRUS GRANULE CELLS Lumei Huang 1,2 , Beáta Sperlágh 2 1 János Szentágothai Doctoral School of Neurosciences, Semmelweis University, Budapest, Hungary 2 Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary. P2X7 receptors (P2rx7) the ligand gated ion channels, regulate a diverse array of normal and pathological brain function, including learning and memory formation, mood and behavior. However, the cellular mechanisms underlying these functions are far from fully explored yet. Therefore, we studied here the involvement of P2X7Rs in excitatory neurotransmission in dentate gyrus granule cells. To address this question, we mainly utilized patch clamping technique with whole cell configuration to record miniature excitatory postsynaptic current (mEPSC) in both wild-type and P2rx7-/- mice under the model of voltage clamp. During recording, Mg 2+ free/low Ca 2+ ACSF solution was bath- applied together with TTX (Na + blocker, 1 µ M) and GABAzine (GABA A antagonist, 10 µ M). To isolate NMDA-mediated mEPSC, CNQX (AMPA/kainate receptor antagonist, 20 µ M) was applied to block AMPA-related events. As for AMPA-mediated mEPSC recording, DL-AP5 (NMDA receptor antagonist, 50 µ M) was used to block NMDA- related events. After each recording, CNQX or DL-AP5 was employed to confirm the events induced by NMDA or AMPA. Furthermore, selective antagonist of P2X7Rs (JNJ-47965567, 10µM) was perfused to replicate the effect of P2rx7 gene deficiency. Finally, the morphological features of studied cell filled with biocytin has been visualized based on confocal images. We found that the amplitude and frequency of NMDA-mediated mEPSC significantly decreased in P2rx7-/- mice compared to WT counterparts whereas JNJ-47965567 decreased the frequency, but not the amplitude. AMPA-mediated mEPSCs were also decreased in in P2rx7-/- mice and JNJ-47965567 replicated these results. To summarize, P2X7Rs participate in the modulation of excitatory neurotransmission partly through an action potential-independent mechanism in adult dentate gyrus granule cells.