Abstract
Despite critical roles of spinal microglia in neuropathic pain in male mice, several lines of evidence suggest that microglial inhibitors have no suppressive effects on that in female mice. However, detail mechanisms underlying sexual dimorphism of microglia in neuropathic pain is still unclear. Here, we evaluated suppressive effects of PLX3397, a colony-stimulating factor 1 receptor inhibitor; microglial inhibitor, on nerve injury-induced neuropathic pain in both sexes. PLX3397 was formulated in normal diet at 290 mg/kg and fed to mice ad libitum. Partial sciatic nerve ligation (PSL)-induced mechanical allodynia, evaluated by von Frey test, was suppressed by PLX3397 in male but not in female mice. Although activation of microglia in the spinal dorsal horn (SDH) was commonly observed in both sexes, suppressive effects of PLX3397 on microglial activation in female mice was less than that in male mice. Moreover, there were some differences in upregulation of inflammatory mediators in the SDH after PSL between male and female mice. Collectively, sexual dimorphism of spinal microglia might underlie resistance to microglial inhibitors in female mice subjected to neuropathic pain.
