CNR1 and obesity due to melanocortin 4 receptor deficiency: Given that expression of CB1 was significantly affected and that activation of CB1 is related to obesity-associated hepatic steatosis, we analyzed the mRNA levels of enzymes involved in the biosynthesis of endocannabinoids [diacylglicerol lipases (DGLα and DGLβ) and N-acyl phosphatidylethanolamine phospholipase D (NAPE-PLD)], degradative enzymes [fatty acid amide hydrolase (FAAH) and monoacylglycerol lipase (MGL)] and the cannabinoid type 2 receptor (CB2) (supplementary material Fig. S1).