Microglia—the resident immune cells in the brain—could be more active in regions involved in pain processing in females than in males, a recent study suggests.

This sex difference in brain microglia between females and males may explain why a higher incidence of chronic and inflammatory pain conditions such as fibromyalgia and osteoarthritis occurs in females than in males, and why chronic pain relief drugs such as morphine and opioids seem to work more effectively in males than in females, notes a media release from Georgia State University.

“Indeed, both clinical and preclinical studies report that females require almost twice as much morphine as males to produce comparable pain relief,” says Hillary Doyle, graduate student in the Murphy Laboratory in the Neuroscience Institute of Georgia State, in the release. “Our research team examined a potential explanation for this phenomenon, the sex differences in brain microglia.”

In their study, published in the Journal of Neuroscience, Doyle and her team gave male and female rats a drug that inhibited microglia activation. Among the female rats with blocked microglia, their response to opioid pain medication improved and matched the levels of pain relief normally seen in males.

“The results of the study have important implications for the treatment of pain, and suggests that microglia may be an important drug target to improve opioid pain relief in women,” states Dr Anne Murphy, co-author on the study and associate professor in the Neuroscience Institute at Georgia State, in the release.

[Source(s): Georgia State University, Science Daily]