Effects of soybean isoflavone on liver lipid metabolism in nonalcoholic fatty liver rats

OBJECTIVE To study the effects of soybean isoflavone on liver lipid, serum lipid, antioxidant index and hepatic lipid metabolism associated factors in nonalcoholic fatty liver rats. METHODS Thirty-six male rats (SD) were randomly divided into four groups by weight: normal control group, nonalcoholic fatty liver disease (NAFLD) model control group, low-dose isoflavone treatment group (10 mg/kg) and high-dose isoflavone group (20 mg/kg), 9 rats in each group. Normal control rats were fed with D12450B (10% fat energy), model control and isoflavone intervention rats were fed with D12492 (60% fat energy). Twelve weeks later, liver lipid, serum lipid and antioxidant index were observed. Liver sterol regulatory element binding protein-1c (SREBP-1c), fatty acid synthase (FAS) and peroxisome proliferators activated receptor alpha (PPAR alpha) were detected by western blotting. RESULTS Liver triglyceride (TG) in normal control group, NAFLD model control group, low-dose isoflavone group and high-dose isoflavone group were (8.11 ± 4.13), (57.06 ± 16.95), (31.26 ± 10.48), (31.38 ± 13.25) mmol/mg protein, respectively (F = 22.569, P < 0.01); liver free fatty acid (FFA) were (0.030 ± 0.007), (0.042 ± 0.009), (0.038 ± 0.009), (0.032 ± 0.005) µmol/mg protein, respectively (F = 4.857, P < 0.01); liver superoxide dismutase (SOD) activity were (502.29 ± 23.71), (201.83 ± 16.99), (228.93 ± 21.71), (238.08 ± 15.96) U/mg protein, respectively (F = 9.555, P < 0.01); liver malondialdehyde (MDA) were (1.29 ± 0.29), (2.85 ± 0.73), (2.07 ± 0.49), (2.03 ± 0.37) nmol/mg protein, respectively (F = 13.449, P < 0.01); SREBP-1c protein expression were 0.45 ± 0.16, 1.42 ± 0.30, 1.02 ± 0.31, 0.47 ± 0.27, respectively (F = 24.515, P < 0.01); FAS protein expression were 0.27 ± 0.08, 1.97 ± 0.47, 1.35 ± 0.30, 0.49 ± 0.12, respectively (F = 60.361, P < 0.01); PPARα protein expression were 2.03 ± 0.56, 0.41 ± 0.17, 0.81 ± 0.27, 0.66 ± 0.16, respectively (F = 37.97, P < 0.01). CONCLUSION Soy isoflavone can reduce the hepatic lipid deposition and increase antioxidant capacity, the mechanism may be related to inhibition of SREBP-1c and activation of PPARα expression in liver.