Massage-like stroking induces pain relief in mice

Chronic pain is a persistent challenge, and the use of pharmaceuticals often comes with undesirable side effects. Manual therapies, including massage, acupuncture, and osteopathic manipulative treatments, have shown promise in providing pain relief to humans. However, the underlying mechanisms behind these therapies have remained elusive, hindering their optimization as safe pain management techniques.

In a recent study, researchers have introduced a murine model that mimics the pain-relieving effects of massage-like stroking (MLS), shedding light on the physiological mechanisms responsible for this analgesic response and offering potential new avenues for pain therapy. The study was published in Neurobiology of Pain, Dec 24, 2023.

A Model for Understanding Pain Relief

The team of scientists from the Department of Physiology at Michigan State University, sought to establish a preclinical model that could help unravel the mystery behind these therapies.  

The mice were divided into three distinct groups: the Massage Group, the Hold-Only Group, and the Control Group.

In the Massage Group, mice received the MLS protocol, which involved a 60-minute massage treatment administered daily for one week.

Meanwhile, in the Hold-Only Group, mice were gently held in the handler’s hand for the same 60-minute duration as the massage treatment. However, they did not receive any MLS treatment.

Lastly, the Control Group served as a baseline comparison, with mice left undisturbed and untouched for the entire 60-minute period, placed in a new cage.

Pain hypersensitivity was induced in mice by making a 5-mm longitudinal incision in the skin of their left hindpaw and the underlying muscle tissue. To assess nociceptive responses in mice, hot plate testing was conducted after a seven-day treatment cycle.

Effective Pain Relief

The study demonstrated that Massage-like Stroking (MLS) significantly increased pain tolerance to noxious heat stimuli in both male and female mice, highlighting its gender-neutral analgesic effect. Stroking, rather than habituation or handler identity, was confirmed as the key factor behind this effect. MLS remained effective whether administered to awake or anesthetized mice, ruling out psychological influences. The research also showed that MLS did not induce anxiety-like behavior in mice. Furthermore, naloxone, an opioid receptor antagonist, did not block MLS-induced analgesia, indicating a non-opioid mechanism.

Massage-like stroke has demonstrated its effectiveness in alleviating thermal pain in mice, even in those with postoperative pain hypersensitivity. This breakthrough suggests that massage-induced analgesia could be a potential avenue for pain relief in various scenarios.