Lesional accumulation of P2X4 receptor+ monocytes following experimental traumatic brain injury

P2X4 receptor (P2X4R) is an ATP-gated ion channel. ATP is an important messenger in traumatic brain injury. Here, we report expression of P2X4R in rat traumatic brain injury with focus on the early phase, most amenable to therapy. Accumulation of P2X4R+ cells was observed as early as 6 h after injury and continued to increase 4 days post-injury at the lesion and remote areas. Double staining revealed that most P2X4R+ cells co-expressed ED-1, a marker for reactive microglia/macrophages, but not nestin or W3/13. Our data suggest that P2X4R expression defines a subtype of activated microglia/macrophages involved in the early processes following traumatic brain injury.