It’s no secret that women and men experience pain differently, and there are a variety of reasons to cause this variance in pain perception. Hormones are known to influence pain sensitivity, body structure affects the density of pain receptors, and psychological and social factors play a role in how pain is perceived and expressed.
With all these factors in mind, it’s surprising to learn that most pain research has historically ignored sex differences. As a result, many studies missed the opportunity to analyze or report these differences. The impact of this gender bias in pain research is clear: Women often struggle more than men to be taken seriously and treated appropriately, according to the International Association for the Study of Pain.
Fortunately, research is improving. Today, studies are asking more questions and including female participants in both preclinical and clinical research. A recent study from University of California San Francisco, published in Science, reveals how the predominantly female hormones estrogen and progesterone help suppress pain by stimulating the production of opioids within the body.
The Immune System’s Role in Pain
Understanding pain requires acknowledging the significant role the immune system plays in it. T cells, which are a type of white blood cell, are known to influence pain amplification, although the exact mechanisms are still not fully understood.
The new study focused on a recently discovered type of T cell called T regulatory cells (T-regs). These cells were found to reduce inflammation and are abundant in the protective layers of the spinal cord, known as the meninges. The research revealed that T-regs use the meninges to communicate with neurons near the skin. To better understand how T-regs function, the researchers used a proven method: they eliminated the cells using a toxin.
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Female Hormones Trigger Painkiller Production
Disabling the T-regs showed an immediate effect: compared to their male counterparts, female mice became significantly more sensitive to pain, highlighting the importance of these immune cells in managing pain in females.
Further investigation revealed that estrogen and progesterone, the primary female sex hormones, caused T-regs to produce the body’s natural painkiller: enkephalin, an opioid-like substance.
“The fact that there’s a sex-dependent influence on these cells – driven by estrogen and progesterone – and that it’s not related at all to any immune function is very unusual,” said lead author Elora Midavaine, a postdoctoral fellow in a press release.
The Future of Pain Management
This discovery leaves the research team excited about the future of pain treatment. They hope to continue exploring the exact mechanisms behind this new pathway, which could lead to more effective pain treatments and raise awareness on the importance of studying the underlying mechanisms of pain management in women.
One potential approach is targeting T-regs directly to increase the production of the painkiller enkephalin, which ultimately would benefit both women and men.
“If that approach is successful, it could really change the lives of the nearly 20% of Americans who experience chronic pain that is not adequately treated,” said co-author Allan Basbaum in the news release.
Understanding the role of sex hormones in pain regulation could also help doctors better support women, especially those going through menopause, who often report struggling with chronic pain. This knowledge could lead to more personalized pain treatments in the future.
This article is not offering medical advice and should be used for informational purposes only.
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Having worked as a biomedical research assistant in labs across three countries, Jenny excels at translating complex scientific concepts – ranging from medical breakthroughs and pharmacological discoveries to the latest in nutrition – into engaging, accessible content. Her interests extend to topics such as human evolution, psychology, and quirky animal stories. When she’s not immersed in a popular science book, you’ll find her catching waves or cruising around Vancouver Island on her longboard.
