CNR1 and obesity due to melanocortin 4 receptor deficiency: Hyper-activation of cannabinoid receptor-1 (CB1) by the endogenous ligands anandamide and 2-arachidonoylglycerol (2-AG) was shown to mediate metabolic abnormalities such as insulin resistance and altered homeostasis of lipids [6], while CB1 antagonists have been implicated in treating metabolic disorders as well as obesity [7].