Cannabis sativa is the source of a unique set of compounds known collectively as plant cannabinoids or phytocannabinoids. This review focuses on the manner with which three of these compounds, ( )-trans-D9 -tetrahydrocannabinol (D9 -THC), ( )- cannabidiol (CBD) and ( )-trans-D9 -tetrahydrocannabivarin (D9 -THCV), interact with cannabinoid CB1 and CB2 receptors. D9 -THC, the main psychotropic constituent of cannabis, is a CB1 and CB2 receptor partial agonist and in line with classical pharmacology, the responses it elicits appear to be strongly influenced both by the expression level and signalling efficiency of cannabinoid receptors and by ongoing endogenous cannabinoid release. CBD displays unexpectedly high...
