The protective effects of Ninjin'yoeito against liver steatosis/fibrosis in a non-alcoholic steatohepatitis model mouse.

Non-alcoholic steatohepatitis (NASH) is a progressive fibrotic form of non-alcoholic fatty liver disease. Liver fibrosis leads to liver cancer and cirrhosis, and drug therapy for NASH remains lacking. Ninjin'yoeito (NYT) has shown antifibrotic effects in a model of liver fibrosis without steatosis but has not been studied for NASH. Therefore, we evaluated the efficacy of NYT in mice fed a choline-deficient, L-amino acid-defined, high-fat diet (CDAHFD) as a NASH model. Compared with the normal diet group, mice fed CDAHFD showed decreased body weight and increased white adipose tissue, liver weight, and triglyceride content in the liver. Furthermore, a substantial increase in the hepatic concentration of hydroxyproline, expression of α-smooth muscle actin (α-SMA), and transforming growth factor-β was observed in CDAHFD-fed mice. Masson's trichrome and Picro-Sirius red staining revealed a remarkable increase in collagen fiber compared with the normal diet group. Compared with mice that received CDAHFD alone, those supplemented with NYT exhibited reduced hepatic triglyceride and hydroxyproline levels and α-SMA expression. Additionally, compared with the group fed CDAHFD alone, the stained liver tissues of NYT-treated mice exhibited a reduction in Masson's trichrome- and Picro-Sirius red-positive areas. Locomotor activity was significantly reduced in the CDAHFD-fed group compared with the normal diet group. In the NYT-treated group, the CDAHFD-induced decrease in locomotor activity was significantly suppressed. The findings indicate that NYT inhibited fatty and fibrotic changes in the livers of NASH mice and alleviated the decrease in locomotor activity. Therefore, NYT may serve as a novel therapeutic approach for NASH.