Previous clinical studies have demonstrated that cannabidiol (CBD) may be effective at relieving pain while also possessing anti-anxiety effects. Cannabidiol is one of the main non-psychoactive components of the hemp plant. While the analgesic and anxiolytic effects of CBD have been widely studied, its effect on serotonin neuronal cell activity, and its impact on models of neuropathic chronic pain, are unknown. A group of researchers from the United States, Canada and Italy conducted a study on rats to determine if CBD could be a viable treatment option for neuropathic pain conditions.
Using in-vivo single-unit extracellular recordings in rats, researchers demonstrated that slowly increasing low doses of CBD decreased the firing rate of serotonin neurons in the dorsal raphe nucleus, the part of the brain stem that contains the majority of serotonin and is linked to stress and emotional processing. Repeated injections of CBD for 7 days, in conjunction with the stimulation of heat receptors, increased serotonin firing through the desensitization of serotonin receptors.
Rats were then subjected to a nerve injury model to induce mechanical allodynia, a nerve condition in which a normal stimulus, such as the touch of clothing, causes debilitating pain. The test subjects were subjected to the nerve injury for 24 days and showed decreased serotonin firing activity, mechanical allodynia and increased anxiety-like behavior during maze tests, open-field tests and novelty-suppressed feeding tests. The subjected rats were then treated with CBD for seven days which reduced mechanical allodynia, decreased anxiety-like behavior and normalized serotonin activity. The study concluded that the repeated low-dose treatments of CBD effectively reduced pain by heat receptor activation and reduced anxiety through serotonin receptor activation.
While more research and trials are required to study this area further, this initial study demonstrates that patients suffering from neuropathic chronic pain conditions could possibly benefit from CBD. To learn more about this study, please click here. https://www.ncbi.nlm.nih.gov/pubmed/30157131