The roles of fractalkine/CX3CR1 system in neuronal death following pilocarpine-induced status epilepticus

Although fractalkine is one of chemokines involved in mediation of neuronal/microglial interaction, it is not known whether fractalkine/CX3CR1-mediated pathogenesis occurs in the rat brain following epileptogenic insults. In order to elucidate the roles of the fractalkine/CX3CR1 system in microglial activation and neurodegeneration induced by status epilepticus (SE), we investigated changes in fractalkine/CX3CR1 system within the rat hippocampus following SE. In non-SE induced animals, fractalkine and CX3CR1 immunoreactivity was detected in neurons and microglia, respectively. Following SE, fractalkine immunoreactivity was transiently increased in neurons and astrocytes. CX3CR1 immunoreactivity was also transiently detected in neurons (particularly in CA1 pyramidal cells). Intracerebroventricular infusions of recombinant rat fractalkine aggravated SE-induced neuronal damage, while fractalkine IgG or CX3CR1 IgG infusion alleviated it, compared to saline-infused animals. These findings suggest that fractalkine/CX3CR1 system may play an important role in SE-induced neuronal damages via neuron-microglial interactions.