Sorge R, Mapplebeck J, Rosen S, Beggs S, Taves S, Alexander J, Martin L, Austin J, Sotocinal S, Chen D, Yang M, Shi X, Huang H, Pillon N, Bilan P, Tu Y, Klip A, Ji R, Zhang J, Salter M, Mogil J (2015) Different immune cells mediate mechanical pain hypersensitivity in male and female mice. Nat Neurosci 18:1081-1083. doi: 10.1038/nn.4053
Summary: A large and rapidly increasing body of evidence indicates that microglia-to-neuron signaling is essential for chronic pain hypersensitivity. Using multiple approaches, the authors found that microglia are not required for mechanical pain hypersensitivity in female mice; female mice achieved similar levels of pain hypersensitivity using adaptive immune cells, likely T lymphocytes. This sexual dimorphism suggests that male mice cannot be used as proxies for females in pain research. Mac-1-SAP mouse/human toxin (Cat. #IT-06, 15 μg in 8.8 μl) and Saporin control (Cat. #PR-01, 8.8 μg in 8.8 μl) were administered via i.t. injection. The topic of immune system involvement in chronic pain pathophysiology is one of the most active in the pain field; that this sex difference has not been observed until now is very surprising indeed. An important implication of the current findings is that distinct strategies targeting neuroimmune signaling might be required for the treatment of chronic pain in men versus women.