Although CB1R is predominantly expressed in mammalian brain, we observed low basal expression of CB1R in many peripheral tissues, and interestingly the liver of humans has a predominant N-terminal intra-exonal spliced isoform (CB1Rb), expression of which is increased by obesity (González-Mariscal et al., 2016). This evidence concerns the gene CNR1 and obesity due to melanocortin 4 receptor deficiency.