Acupuncture, the traditional Chinese practice of inserting very thin needles into the skin at specific points on the body, has never been fully understood in the language of Western medicine. Patients often get pain relief from the treatment, but beyond the placebo effect, researchers often can’t figure out why.

However, a new study in the journal Endocrinology provides evidence that acupuncture is more than just a placebo. In rats, stimulating acupuncture points can mute activity in a chronic stress pathway, researchers from Georgetown University Medical Center found.

In humans, the hypothalamus-pituitary-adrenal (HPA) axis is linked to an acupuncture point on the shin. A similar point is found on the paws of rats. The researchers exposed groups of rats to stress in the form of cold conditions, then saw how they reacted to stimulation on that acupuncture point. They found that the acupuncture seemed to reduce activity in the HPA axis, blocking the production of stress hormones that would normally be part of the body’s chronic stress response, similar to the way some anti-depressants and anti-anxiety medications work.

Obviously, more research into human responses to acupuncture is necessary before we can say for sure how the practice affects the body exactly, but this does indicate that the traditional Chinese medicine technique is more than just the placebo treatment some doctors think it is.

[h/t: Popular Science]