FGF21 deletion mildly exacerbates hepatic dysfunction in GAN diet and alcohol fed rats.

Fibroblast growth factor 21 (FGF21) analogues are in clinical development as treatments for metabolic and alcohol-associated liver disease. The aim of this study was to characterize the first FGF21 knockout (KO) rat line to validate its utility as a translational animal model that recapitulates human disease. We generated an FGF21 KO rat model and exposed 6-month-old WT and KO rats to either chow (n = 8 per genotype) or the obesogenic GAN (Gubra Amylin NASH) diet (n = 16 per genotype) for 12 weeks. Lack of endogenous FGF21 increased plasma transaminases, liver weight, and total levels of liver TG in GAN-fed FGF21 KO rats. FGF21 KO had no impact on body weight, glycaemic traits, or MASH histological endpoints, including hepatic steatosis, NAS score, lobular inflammation, ballooning degeneration, fibrosis stage, or the liver transcriptome. Finally, we demonstrate that endogenous FGF21 does not regulate drinking behaviour in rats.