NEW findings reveal underlying sex differences in processing pain.
The study, published recently in Nature Neuroscience, shows for the first time that male and female mice use different cells to process pain. This demonstrates that men and women have different sensitivity to pain, a departure from the traditional assumption that the wiring of how pain is processed is the same in both sexes, said co-senior author Jeffrey Mogil, Ph.D., E.P. Taylor Professor of Pain Studies at McGill University and director of the Alan Edwards Centre for Research on Pain.
The research further reveals that more women suffer from chronic pain than men.
The study shows that the longstanding theory that pain is transmitted from the site of injury or inflammation through the nervous system using an immune system cell called microglia is true only in male mice. Interfering with the function of microglia in a variety of different ways effectively blocked pain in male mice, but had no effect in female mice.
“The realization that the biological basis for pain between men and women could be so fundamentally different raises important research and ethical questions if we want to reduce suffering,” said Dr. Mogil.
In addition to altering our basic understanding of pain, this could influence future development work on medications for chronic pain, the most prevalent human health condition. It could also change how mice are used in basic biomedical research. With mice having very similar nervous systems to humans, in particular a basic evolutionary function such as pain, the findings point to important questions for human pain drug development.
Dr. Mogil said that scientists have thought that microglia controlled the volume knob on pain for the past 15 years based on research using almost exclusively male mice.
“This finding is a perfect example of why this policy, and very carefully designed research, is essential if the benefits of basic science are to serve everyone,” he added.
According to Michael Salter, M.D., Ph.D., head and senior scientist, Neuroscience & Mental Health at SickKids and professor at The University of Toronto and a co-senior author, “Understanding the pathways of pain and sex differences is absolutely essential as we design the next generation of more sophisticated, targeted pain medications.”