Study Shows Men and Women Process Pain Signals Differently

Researchers from Eastern Canada and Yale University have discovered that neurons in the spinal cord process pain signals differently depending on gender, potentially leading to better and more personalized treatments for chronic pain. 

Unlike most pain research that uses male rodents, the study used female and male spinal cord tissue from both rats and humans. The tissue from humans was donated by deceased individuals and their families.

The researchers were able to show that a neuronal growth factor called BDNF plays a major role in amplifying spinal cord pain signaling in male humans and male rats, but not in female humans or female rats. When female rats had their ovaries removed, the difference disappeared, suggesting a hormonal connection.

“Developing new pain drugs requires a detailed understanding of how pain is processed at the biological level,” says Dr. Annemarie Dedek, lead author of the study and now a MITACS- and Eli Lilly-funded industrial research fellow at Carleton University and The Ottawa Hospital. “This new discovery lays the foundation for the development of new treatments to help those suffering from chronic pain.”

Women are disproportionately impacted by chronic pain, being more likely than men to report low back pain, neck pain, orofacial pain and neuropathic pain. In quantitative evaluation of experimentally induced pain in humans, women show more pain sensitivity than men across several noxious modalities, including mechanical-, electrical-, thermal- and chemical-induced pain. “Given these epidemiological and clinical sex differences and the rising health crisis of poorly managed chronic pain, it is essential to systematically investigate the neurobiological underpinnings of pain processing in both sexes,” the authors say.

The study markets the first time a sex-related difference in pain signaling has been identified in human spinal cord tissue. Future studies are required to understand how this biological difference may contribute to differences in pain sensation between men and women.

“With exciting recent advances in voltage-sensitive dye imaging, multielectrode array recording and single-cell sequencing approaches, researchers can now investigate the impact of dynamic and degenerate signaling pathways on human spinal pain processing,” according to the paper, published recently in the journal Brain. “Our results therefore highlight the critical need for foundational studies using both sexes, as well as the importance of using human preclinical models to improve translation between basic science and clinical medicine in the field of pain research and beyond.”