Augmenting CX3CR1 signaling may protect against microglial neurotoxicity, whereas CNS penetration by pharmaceutical CX3CR1 antagonists could increase neuronal vulnerability;The neuroprotective action of CX3CL1 in different models of brain injuries is mediated by its inhibitory activity on microglia [...] In apparent contrast with the above reported data but in agreement with previous findings, cx3cl1-/- and cx3cr1(GFP/GFP) mice, respectively, deficient in CX3CL1 or CX3CR1, had less severe brain injury on pMCAO, and the administration of exogenous CX3CL1 increased brain damage in cx3cl1-/- ischemic mice.