Abstract
BackgroundIn the present study, we investigated the roles of P2X7 receptor in recruitment and infiltration of neutrophil during epileptogenesis in rat epilepsy models.MethodsStatus epilepticus (SE) was induced by pilocarpine in rats that were intracerebroventricularly infused with either saline, 2',3'-O-(4-benzoylbenzoyl)-adenosine 5'-triphosphate (BzATP), adenosine 5'-triphosphate-2',3'-dialdehyde (OxATP), or IL-1Ra (interleukin 1 receptor antagonist) prior to SE induction. Thereafter, we performed immunohistochemical studies for myeloperoxidase (MPO), CD68, interleukin-1β (IL-1β), monocyte chemotactic protein-1 (MCP-1) and macrophage inflammatory protein-2 (MIP-2).ResultsIn saline-infused animals, neutrophils and monocytes were observed in frontoparietal cortex (FPC) at 1 day and 2 days after SE, respectively. In BzATP-infused animals, infiltrations of neutrophils and monocytes into the FPC were detected at 12 hr and 1 day after SE, respectively. In OxATP-infused animals, neutrophils and monocytes infiltrated into the FPC at 1 day and 2 days after SE, respectively. However, the numbers of both classes of leukocytes were significantly lower than those observed in the saline-infused group. In piriform cortex (PC), massive leukocyte infiltration was detected in layers III/IV of saline-infused animals at 1-4 days after induction of SE. BzATP or OxATP infusion did not affect neutrophil infiltration in the PC. In addition, P2X7 receptor-mediated MCP-1 (released from microglia)/MIP-2 (released from astrocytes) regulation was related to SE-induced leukocyte infiltration in an IL-1β-independent manner.ConclusionsOur findings suggest that selective regulation of P2X7 receptor-mediated neutrophil infiltration may provide new therapeutic approaches to SE or epilepsy.
Highlights
In the present study, we investigated the roles of P2X7 receptor in recruitment and infiltration of neutrophil during epileptogenesis in rat epilepsy models
Restricted blood-derived leukocyte infiltration was observed in the frontoparietal cortex (FPC) and piriform cortex (PC) during the time-window applied in the present study
BzATP or OxATP infusion did not affect neutrophil infiltration in the PC (Figures 2B5, 2C5 and 3B)
Summary
We investigated the roles of P2X7 receptor in recruitment and infiltration of neutrophil during epileptogenesis in rat epilepsy models. The PILO-induced status epilepticus (SE) model replicates the cell type-specific pattern of neuron loss and axon reorganization found in many patients with temporal lobe epilepsy [13,14]. It replicates a common clinical history of patients with temporal lobe epilepsy [15], in that a brain injury precedes a seizure-free latent period before spontaneous, recurrent seizures begin. PILO-induced SE affects WBC infiltration, cytokine levels, and BBB integrity [16] This model is useful for study epileptogenesis, and inflammatory responses induced by SE
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