Bone formation is stimulated by cannabinoid receptors, which suggests that cannabinoid drugs such as marijuana may be a useful treatment for bone diseases and fractures.
Given the recent moves to legalize marijuana for medicinal purposes across many states, researchers are now reinvestigating what beneficial properties this long-prohibited drug may have.
The results of these studies so far have been mixed. A systematic review of 79 randomized clinical trials assessing the effectiveness of cannabinoids - the drug's active compounds - found that the evidence to support marijuana for medical use was low.
Nevertheless, support for medical marijuana remains strong and is likely to be bolstered by the findings of a recent study that reported success in isolating the unwanted side effects of marijuana from its intended medical applications.
Cannabinoid receptors are a kind of receptor native to our bodies that can be activated by compounds in the cannabis plant.
Previously, researchers from Tel Aviv University (TAU) and Hebrew University in Israel found that the skeleton is regulated by cannabinoids and that bone formation is stimulated by cannabinoid receptors within the body, which inhibits bone loss. This finding suggested that cannabinoid drugs may be a useful treatment for bone-related diseases such as osteoporosis.
"The clinical potential of cannabinoid-related compounds is simply undeniable at this point," says Dr. Yankel Gabet, of the Bone Research Laboratory at the Department of Anatomy and Anthropology at TAU's Sackler Faculty of Medicine.
"While there is still a lot of work to be done to develop appropriate therapies," he adds, "it is clear that it is possible to detach a clinical therapy objective from the psychoactivity of cannabis. CBD [cannabidiol], the principal agent in our study, is primarily anti-inflammatory and has no psychoactivity."
Cannabidiol 'boosts bone healing'
- Cannabinoid receptors are activated by a naturally occurring neurotransmitter in the body called anandamide
- THC mimics the actions of anandamide and binds with cannabinoid receptors
- When THC binds with cannabinoid receptors in the brain, it interferes with short-term memory, coordination, learning and problem-solving.
In the new study, published in the Journal of Bone and Mineral Research, Dr. Gabet's team examined the effect of CBD on rats with mid-femoral fractures.
One group of rats was injected with CBD, and another with a combination of CBD and tetrahydrocannabinol (THC) - the main psychoactive component of marijuana.
The team reports that CBD alone was associated with a "markedly enhanced" healing process in the femora after 8 weeks. Dr. Gabet says of the results:
"We found that CBD alone makes bones stronger during healing, enhancing the maturation of the collagenous matrix, which provides the basis for new mineralization of bone tissue. After being treated with CBD, the healed bone will be harder to break in the future."
As other studies have shown CBD to be safe, Dr. Gabet says that researchers "should continue this line of study in clinical trials to assess its usefulness in improving human fracture healing."
Despite concerns that the legalization of marijuana for medical purposes would see an increase in usage of the drug for recreational purposes, a recent study in The Lancet Psychiatry found that - among adolescents - this has not been the case.