OPRD1 and cannabis dependence: Increased expression of Oprd1 gene (encoding opioidergic 1d receptors) and decreased expression of Cnr1 (encoding cannabinoid receptor 1, associated with cannabis dependence and abuse) and Faah (fatty acid amide hydrolase, which catalyzes the hydrolysis of the endocannabinoid 2-arachidonoylglycerol) were found in comparison with the control (C vs. A20 comparison; Figure 3; Supplementary Table S1).