Study: CBD May Reduce a Key Ketamine Side Effect While Preserving Antidepressant Potential
- Researchers found that cannabidiol (CBD) reduces ketamine-induced hyperlocomotion, a major side effect linked to increased dopamine activity, by acting on the brain's ventral tegmental area (VTA).
- CBD administration, both systemically and directly into the VTA, decreased ketamine-triggered neuronal activity in the VTA, prefrontal cortex, and nucleus accumbens, regions involved in reward and motivation.
- CBD's effects were mediated through glycine receptors (GlyRα1) in VTA neurons, reversing ketamine-induced suppression of these receptors and restoring their normal function.
- Mice with a mutated GlyRα1 receptor did not respond to CBD's mitigating effects on hyperlocomotion, highlighting this receptor's crucial role and suggesting potential for targeted treatment development.
A study published online today by the journal Biological Psychiatry reports that cannabidiol (CBD) may help reduce a major side effect of ketamine by targeting a specific receptor in the brain tied to movement and dopamine activity. Researchers from the University of Science and Technology of China examined how CBD interacts with ketamine in mice, focusing on the ventral tegmental area, or VTA, a brain region involved in reward, motivation and dopamine signaling. Although ketamine is known for producing rapid antidepressant effects, it can also trigger psychoactive side effects, including hyperlocomotion, which is linked to heightened dopaminergic activity.
In the study, researchers found that CBD blocked ketamine-induced hyperlocomotion after both systemic administration and direct administration into the VTA. Whole-brain imaging showed that ketamine caused increased neuronal activity in the VTA, prefrontal cortex and nucleus accumbens, and that this heightened activity was reduced when CBD was administered into the VTA and prefrontal cortex.
The findings indicate that CBD’s effect was mediated through glycine receptors, specifically GlyRα1, in VTA neurons. According to the study, ketamine suppressed glycine receptor function, while CBD reversed that dysfunction by counteracting ketamine-driven delays in receptor activation. Researchers also found that CBD blocked ketamine-induced dysfunction of postsynaptic glycine receptors in the VTA.
When researchers tested mice with a specific GlyRα1 mutation, CBD no longer reduced ketamine-induced hyperlocomotion, providing further evidence that this signaling pathway is central to the effect.
The study’s authors say the results show that CBD may help separate ketamine’s therapeutic benefits from at least some of its adverse effects, while also pointing to a specific molecular site that could be useful in the development of more precise treatments.