P2X7 Receptor Inhibition Mitigates Microglial Activation, Neuroinflammation, and Secondary Thalamic Damage After...

Secondary damage in remote brain regions following ischemic stroke significantly worsens patient outcomes, yet its underlying mechanisms remain poorly understood. Microglial activation is a central pathological feature of secondary damage, with the P2X7 receptor (P2X7R) emerging as a key regulator of neuroinflammatory processes. In this study, we employed a distal middle cerebral artery occlusion (dMCAO) model in rats to investigate the role of P2X7R in secondary damage in the ventral posterolateral nucleus (VPN) of the ipsilateral thalamus. We observed a spatiotemporal pattern of microglial activation and elevated P2X7R expression in the VPN, coinciding with delayed neuronal loss and gliosis. P2X7R activation drove the NLRP3 inflammasome cascade, leading to the release of interleukin-1β (IL-1β). Inhibition of P2X7R using Brilliant Blue G (BBG) significantly attenuated microglial activation, suppressed the NLRP3/IL-1β axis, and reduced neuronal loss and gliosis in the VPN. Molecular dynamics simulations confirmed BBG's high-affinity binding to P2X7R, while behavioral tests demonstrated improved neurological function. Transcriptome sequencing revealed that P2X7R inhibition by BBG induces profound reprogramming of calcium signaling pathways, suppressing calcium-regulated exocytosis and neuroactive ligand-receptor interactions, while enriching the cAMP pathway. This correlates with BBG's efficacy in attenuating microglial activation, NLRP3/IL-1β axis activation, and neuronal loss. Our findings establish P2X7R as a central driver of neuroinflammation in delayed neurodegeneration after ischemic stroke,and inhibition with P2X7R offers a promising strategy to mitigate secondary damage.