Fig. 4
Empagliflozin (EMPA) increased liver catechol-O-methyltransferase (COMT) activity and ameliorated liver fibrosis in diabetic mice. (a) A methyltransferase assay kit, which detects the S-adenosylhomocysteine (SAH) reaction product, was used to measure the liver SAH concentration in db/ +, db/db control and db/db EMPA mice. Norepinephrine (NE) was used as a substrate, and tolcapone was used as a COMT inhibitor. (b) The difference in liver SAH between samples with and without NE (ΔSAH), which represents liver COMT activity, was calculated. (c) Liver membrane-bound (MB), soluble (S), and total COMT protein levels were analysed using western blotting. The data were normalised to those of β-actin. Original blots are presented in Supplementary Fig. S5. (d) Immunohistochemistry analysis was performed on the liver. The scale bar represents 200 µm. (e) Sirius red staining was performed on the liver. The scale bar represents 100 µm. (f) Liver α-smooth muscle actin (αSMA) protein levels were analysed using western blotting. Original blots are presented in Supplementary Fig. S6. db/ +, n = 5. db/db control, n = 6. db/db EMPA, n = 6. The data are presented as the mean ± SEM. The data were analysed using one-way ANOVA followed by Tukey’s test. *p < 0.05, **p < 0.01, ***p < 0.001, ****p < 0.0001.
