Western University researchers have, for the first time, demonstrated the molecular mechanisms that come into play to make cannabidiol or CBD block the psychiatric side-effects of tetrahydrocannabinol (THC), which is the main psychoactive chemical in cannabis. Steven Laviolette, Ph.D., and his team of researchers used rats to examine the role of a molecule in the brain’s hippocampus known as an extracellular signal-regulated kinase (ERK) that triggers the neuropsychiatric effects of THC. Laviolette, Professor, Schulich School of Medicine & Dentistry, Western University, explains that their findings have, for the first time, identified the molecular mechanisms by which CBD might inhibit these THC-related side effects. The team’s results have been published in the Journal of Neuroscience.
It has already been proven that strains of cannabis having high levels of THC and low levels of CBD can cause increased psychiatric effects such as anxiety, addictive-behaviors, and paranoia; however, the way it happens remains unknown. In the study, the rats that were administered THC had higher levels of activated ERK, displayed more anxious behaviors, and were more sensitive to fear-based learning. Rats that received both CBD and THC acted like the control rats with normal levels of activated ERK, less anxiety, and lower sensitivity to fear-based learning. Based on their results, the team proposes that CBD blocks the ability of THC to overstimulate the ERK pathway in the hippocampus, preventing negative side effects. Laviolette says that their findings have potential implications pertaining to the prescription of cannabis and long-term cannabis usage.
Roger Hudson, Doctoral Candidate, Vanier Scholar, and lead author of the study highlights another remarkable finding of the research, suggesting that CBD alone had no impact on the ERK pathway, although, by co-administering CBD and THC, the team entirely reversed the direction of the change on a molecular level. Hudson says that CBD was also able to reverse anxiety and addictive behavior caused by THC. Laviolette says that they will continue to identify the distinctive features of the molecular mechanism, while also discovering ways to formulate THC with fewer side effects and enhance the efficacy of CBD-based therapies.