Georgia: A female brain’s resident immune cells are more active in regions involved in pain processing relative to males, according to a recent study by Georgia State University researchers.The study, published in the Journal of Neuroscience, found that when microglia, the brain’s resident immune cells, were blocked, female response to opioid pain medication improved and matched the levels of pain relief normally seen in males.
Women suffer from a higher incidence of chronic and inflammatory pain
conditions such as fibromyalgia and osteoarthritis. While morphine
continues to be one of the primary drugs used for the treatment of
severe or chronic pain, it is often less effective in females.
“Indeed, both clinical and preclinical studies report that females
require almost twice as much morphine as males to produce comparable
pain relief,” said Hillary Doyle, graduate student in the Murphy Laboratory in the Neuroscience Institute
of Georgia State. “Our research team examined a potential explanation
for this phenomenon, the sex differences in brain microglia.”
In healthy individuals, microglia survey the brain, looking for signs
of infection or pathogens. In the absence of pain, morphine interferes
with normal body function and is viewed as a pathogen, activating the
brain’s innate immune cells and causing the release of inflammatory
chemicals such as cytokines.
To test how this sex difference affects morphine analgesia, Doyle
gave male and female rats a drug that inhibits microglia activation.
“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,” said Dr. Anne Murphy, co-author on the study and associate professor in the Neuroscience Institute at Georgia State.
The research team’s finding that microglia are more active in brain
regions involved in pain processing may contribute to why the incidence
rates for various chronic pain syndromes are significantly higher in
females than males.
Read the study → http://www.jneurosci.org/content/early/2017/02/20/JNEUROSCI.2906-16.2017