“To better understand why male and female mice dealt with pain so differently, Sorge and Mogil turned to a pain source that affects all mice. They injured the animals’ sciatic nerves, which run from the lower back down each leg. This led to a form of chronic pain that happens when the body’s pain-detecting system is damaged or malfunctioning. It caused both male and female mice to become extra sensitive to touch.
“Yet even in this case, there were differences. Microglia seemed to have a prominent role in the pain of males, but not in that of female mice2. Sorge and a team of collaborators from three institutions found that, no matter how they blocked microglia, this eliminated the pain hypersensitivity in males alone.
“It’s not that females were immune to pain. They were just as bothered by nerve injury as the males were, but they weren’t using microglia to become hypersensitive to touch. Mogil and Sorge wondered whether another immune component, called a T cell, was behind the chronic pain in females. These cells have a known role in pain sensitization in mice.
“Sorge tried the same nerve injury in female mice lacking T cells. They still became hypersensitive to the fine hairs, but the mechanism now seemed to occur through microglia. In females lacking T cells, blocking the activity of microglia prevented this pain response, just as it did in males. And when the researchers transferred T cells back to female mice that were lacking them, the animals stopped using microglia in nerve-injury pain (see ‘Two routes to pain’).”
Read Amber Dance’s full article at Nature: Why the Sexes Don’t Feel Pain the Same Way