Australian scientists report that CBD acts as a “positive allosteric modulator” of the GABA-A receptor. In other words, CBD interacts with the GABA-A receptor in a way that enhances the receptor’s binding affinity for its principal endogenous agonist, gamma-Aminobutyric acid (GABA), which is the main inhibitory neurotransmitter in the mammalian central nervous system. The sedating effects of Valium and other Benzos are mediated by GABA receptor transmission. CBD reduces anxiety by changing the shape of the GABA-A receptor in a way that amplifies the natural calming effect of GABA.
CBD also functions as an allosteric receptor modulator, which means that it can either enhance or inhibit how a receptor transmits a signal by changing the shape of the receptor.
Canadian scientists have identified CBD as a “negative allosteric modulator” of the cannabinoid CB1 receptor, which is concentrated in the brain and central nervous system. While cannabidiol doesn’t bind to the CB1 receptor directly like THC does, CBD interacts allosterically with CB1 and changes the shape of the receptor in a way that weakens CB1’s ability to bind with THC.
As a negative allosteric modulator of the CB1 receptor, CBD lowers the ceiling on THC’s psychoactivity—which is why people don’t feel as “high” when using CBD-rich cannabis compared to when they consume THC-dominant medicine. A CBD-rich product with little THC can convey therapeutic benefits without having a euphoric or dysphoric effect.