Src Family Kinases Activity is Required for Transmitting Purinergic P2X7 Receptor Signaling in Cortical Spreading Depression and Neuroinflammation

Abstract

Background Purinergic P2X7 receptor plays a key role in migraine pathophysiology. Yet precise molecular mechanism underlying P2X7R signaling in migraine remains unclear. This study explores the hypothesis that P2X7 receptor transmits signaling to Src family kinases (SFKs) during cortical spreading depression (CSD) and CSD-induced neuroinflammation. Methods CSD was recorded using electrophysiology in rats, and intrinsic optical imaging in mouse brain slices. Cortical IL-1β and TNFα mRNA expression were detected using qPCR. Glutamate release in mouse brain slices was detected using glutamate assay. Results The data showed that systematic deactivation of SFKs by PP2 reduced cortical susceptibility to CSD in rats and CSD-induced IL-1b and TNF-a gene expression in rat ipsilateral cortices. Consistently, in mouse brain slices, inhibition of SFKs activity by saracatinib and P2X7 receptor by A740003 similarly reduced cortical susceptibility to CSD. When the interaction of P2X7 receptor-SFKs was disrupted by TAT-P2X7, a marked reduction of cortical susceptibility to CSD, CSD-induced IL-1b gene expression and glutamate release were observed in mouse brain slices. The reduced cortical susceptibility to CSD by TAT-P2X7 was restored by NMDA and disrupting Fyn-NMDA interaction using TAT-Fyn (39-57), but not disrupting Src-NMDA receptor using TAT-Src (40-49), reduced cortical susceptibility to CSD. Furthermore, activation of P2X7 receptor by BzATP restored the TAT-Fyn (39-57)-reduced cortical susceptibility to CSD. Conclusion This study reveals that SFKs activity mediates P2X7 receptor pore formation facilitating CSD propagation, CSD-induced neuroinflammation and glutamate release, of particular relevance to migraine.