Selective depletion of gut-derived 5-HT by genetic ablation of gut TPH1 (villin-cre: tph1fl/fl) improves HFD-induced liver steatosis and triglyceride accumulation, but does not affect other systemic energy metabolism features, such as body weight, plasma cholesterol and triglycerides, glucose tolerance, and adiposity, suggesting that gut-derived 5-HT is specifically involved in liver lipogenesis 198. Here, TPH1 is linked to fatty liver disease.