Are cannabidiol and Δ9-tetrahydrocannabivarin negative modulators of the endocannabinoid system? A systematic review John M McPartland, Marnie Duncan, Vincenzo Di Marzo and Roger G Pertwee British Journal of Pharmacology, 2015, 172, 737-753. Doi : 10.1111/bph.12944   Based upon evidence that the therapeutic properties of Cannabis preparations are not solely dependent upon the presence of Δ9-tetrahydrocannabinol (THC), pharmacological studies have been recently carried out with other plant cannabinoids (phytocannabinoids), particularly cannabidiol (CBD) and Δ9-tetrahydrocannabivarin (THCV). Results from some of these studies have fostered the view that CBD and THCV modulate the effects of THC via direct blockade of cannabinoid CB1 receptors, thus behaving like first-generation CB1 [...]