Using rat models of osteoarthritis, scientists at the University of Nottingham found that synthetic cannabinoids could relieve pain by interfering with signals at the spinal cord level.

The study, published last month in the open-access journal PLOS One, looked at specific marijuana pathways called CB2 receptors, which the authors note have "well described anti-inflammatory effects" when activated.

They conclude that cannabinoids which activate these pathways may hold promise in treating osteoarthritis, especially during early stages of the disease.

"Our clinical and pre-clinical data support the further investigation of the potential of CB2 receptor agonists for the treatment of pain associated with OA (osteoarthritis), in particular at earlier stages of the disease."

Interestingly, the scientists observed significant changes in the expression of cannabinoid pathways in tissue samples taken from both rats and humans with osteoarthritic joint damage, suggesting that the body naturally facilitates this mechanism of pain relief.

"We report the first evidence for the expression of CB2 mRNA in the human spinal cord, and demonstrate a negative correlation with joint chondropathy (damage). A positive correlation between the extent of chondropathy and pain has previously been reported, supporting the clinical utility of this approach."

Despite the lack of human trials, patients with arthritis have long reported marijuana to be helpful.

According to Jason J. McDougall, PhD, an Associate Professor of Pharmacology and Anaesthesia at Dalhousie University, who was not involved with the study, arthritis patients represent the largest group of Canadians using medical marijuana for any specific condition.

Statistics from Health Canada and the Canadian Consortium for the Investigation of Cannabinoids (CCIC) show that 36% of medical marijuana patients in Canada use the drug to treat some form of arthritis.

Although researchers seem to be taking a special interest in synthetic cannabinoids, Dr. McDougall believes that natural cannabis also needs to be considered "as a way of managing pain effectively."

The study received funding from Arthritis Research U.K. and the National Institutes of Health (NIH)

Source: LeafScience