LEPR and metabolic dysfunction-associated steatotic liver disease: In order to explore whether the hepatic injury in HFD-fed metformin-treated ZDF rats is directly affected by Lepr deficiency, we analyzed the serological indexes and liver pathology of Lepr wild type (WT) rats and Lepr knock-out (KO) rats with HFD-induced NAFLD, with and without metformin administration.