Scientists at the University of California, San Francisco, have identified a unique mechanism of natural pain relief: T cells close to the spinal cord can produce enkephalin, a natural painkiller that is activated by the female sex hormones estrogen and progesterone.
This has been described as a kind of “internal morphine.” Unlike pharmacological opioids, the response does not cause addiction. The highest activity of this reaction was observed in female mice, pointing to differences in immune and hormonal responses between the sexes. The effect may help explain why women in menopause—when hormone levels decline—more often experience chronic pain.
The researchers are working on modifying T cells so they could produce pain relief regardless of sex. They are also developing synthetic estrogen analogs that activate only the needed receptors in the immune system, aiming to avoid hormonal side effects.
In the future, this could mean relying more on the body’s own capabilities instead of “heavy artillery” from pharmacology.
