Receptors for the body’s own cannabinoid substances are present in muscle fascia — soft connective tissue surrounding all muscles and involved in several pain states, according to recent research from the University of Padua in Italy.
In addition to casting light on disease processes in fibromyalgia, the findings might lead to better approaches for managing pain and inflammation in the disease, for which current treatments often fail to adequately treat symptoms.
Endocannabinoids are bodily substances chemically resembling the cannabinoid molecules in cannabis. The factors send signals through two receptors that scientists have primarily explored in the brain and in immune cells, and studies show that stimulating the receptors can relieve pain and suppress inflammation.
Patients with pain conditions such as fibromyalgia often turn to cannabis when prescription drugs are not enough to manage their symptoms. A 2005 study from the United Kingdom listed fibromyalgia among those conditions where patients frequently turn to marijuana for symptom relief, and a 2014 study of 217 U.S. patients showed that pain was the most commonly reported ailment in patients who use medical cannabis.
Research has also demonstrated that patients with fibromyalgia report that marijuana use lowers pain and improves health-related quality of life, making researchers suspect that endocannabinoid receptors, which also mediate the effects of marijuana, might exist in tissues other than the brain and immune cells.
To explore this, the study, “Expression of the endocannabinoid receptors in human fascial tissue,“ published in the European Journal of Histochemistry, turned to muscle fascia, a tissue that has also been linked to other muscle pain conditions.
Extracting the tissue from thigh muscles of 11 volunteers who had orthopedic surgery, researchers isolated the main cell type of the fascia, called fibroblasts. They found both types of receptors, called CB1 and CB2, in the cells. Examining whole tissue levels of the two receptors, researchers noted somewhat higher levels, indicating that the receptors may also be present in other cell types.
A better understanding of how endocannabinoid receptors are involved in fibromyalgia might lead to treatments specifically targeting the receptors in the muscles, avoiding the effects of manipulating cannabinoid receptors in the brain which mediate the psychotropic actions of cannabis.