Cannabinoids Help Scientists Explain Mysterious Stress-Pain Relationship

Heightened pain in individuals who are stressed, anxious or depressed is widely recognized by scientists. While the link between mood and pain perception is poorly understood, genetic factors have long been thought to play a part.

Now researchers have connected a stress-prone genetic background with a dampened response of endocannabinoids – natural chemicals that act to decrease pain – in a region of the brain called the rostral ventromedial medulla. The region is known to play a role in regulating pain.

Dr David Finn, of the Galway Neuroscience Centre and the Centre for Pain Research at the National University of Ireland (NUI), shared his thoughts on the new findings in Wednesday’s press release.

“The link between emotionality and pain is fascinating and highly complex. This research suggests a key role for the brain’s endocannabinoid system in a genetic background prone to heighted stress or negative emotion.”

He adds that the findings could lead to new treatments of pain and stress-related psychiatric disorders.

The study, published online in the journal PAIN, pinpointed CB1 receptors in the rostral ventromedial medulla as a site of action for the brain’s cannabinoid painkillers. CB1 receptors are also activated by THC in marijuana and a responsible for the drug’s psychoactive effects.

Previous studies have also shown a pain-relieving effect of CB1 receptors in this region of the brain. However, Dr. Finn’s study was the first to link irregular endocannabinoid activity in the rostral ventromedial medulla to genetic stress factors.

The authors conclude that reversing the irregular activity may “represent a useful and novel therapeutic approach for the treatment of patients with pain that is exacerbated by negative affect or co-morbid with stress-related psychiatric disorders.”

The study received funding from the Science Foundation Ireland