Peripheral nerve injury induces substantial molecular changes in the somatosensory system that leads to maladaptive plasticity and cause
neuropathic pain. Understanding the molecular pathways responsible for the development of
neuropathic pain is essential to the development of novel rationally designed
therapeutics. Although
lipids make up to half of the dry weight of the spinal cord, their relation with the development of
neuropathic pain is poorly understood. We aimed to elucidate the regulation of spinal
lipids in response to neuropathic
peripheral nerve injury in mice by utilizing matrix-assisted
laser desorption/ionization imaging mass spectrometry, which allows visualization of
lipid distribution within the cord. We found that
arachidonic acid (AA) containing [PC(diacyl-16:0/20:4)+K]+ was increased temporarily at superficial ipsilateral dorsal horn seven days after spared nerve injury (SNI). The spatiotemporal changes in
lipid concentration resembled microglia activation as defined by ionized
calcium binding adaptor molecule 1 (Iba1) immunohistochemistry. Suppression of microglial function through
minocycline administration resulted in attenuation of
hypersensitivity and reduces [PC(diacyl-16:0/20:4)+K]+ elevation in the spinal dorsal horn. These data suggested that AA containing [PC(diacyl-16:0/20:4)+K]+ is related to
hypersensitivity evoked by SNI and implicate microglial cell activation in this
lipid production.