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When it comes to pain, are we all equal?

About 90% of fibromyalgia patients are women, and women are twice as likely as men to suffer from headaches and migraines. Yet men tend to be hypersensitive to pain felt a second time in the same context.

Now, science understands why: the neural mechanisms involved in pain differ, in part, according to biological sex.

Those are the findings of years of research by Yves De Koninck, professor in the Faculty of Medicine and member of the Cervo Brain Research Centre at Université Laval, and his Canadian* and American** collaborators.

De Koninck and his colleagues observed that the BDNF protein produced by microglia—the cells that defend the nervous system—sends a typically male pain signal, increasing pain sensitivity for short periods in male rats but not in females. Analyses on post-mortem human spinal cord tissue have confirmed the observation. The explanation may be hormonal, since BDNF also activates pain in female mice that no longer produce sex hormones following ovarian resection.

As part of another project, the teams led by Theodore Price and Yves De Koninck showed that the CGRP peptide exacerbates pain in biological women, which may explain why migraines are common in women.

For Yves De Koninck, it is essential to broaden the research into sex differences in pain signals to eventually adapt treatment options.

* Michael Hildebrand, researcher in the Department of Neuroscience at Carleton University, and Jeffrey Mogil, researcher in the Department of Psychology at McGill University.

** Theodore Price, researcher in the Faculty of Neuroscience at the University of Texas at Dallas.