Given the widespread functional role of brain-derived neurotrophic factor (BNDF) released by microglia in physiological processes involved in learning and memory (24) and also in pathological events such as neuronal disinhibition of the intrinsic inhibitory system, causing neuropathic pain after peripheral nerve injury (25, 26), we evaluated the impact of the developmental state on gene regulation of microglial BNDF after repeated challenge with LPS. This evidence concerns the gene BDNF and peripheral nerve injury.