Objective: To explore the dose-effect and mechanism of the protective effect of corn peptide(CP) on nonalcoholic fatty liver disease(NAFLD).
Methods: Seventy male SD rats were randomly divided into control group, model group, CP group, puerarin positive control group, low-, medium-, high-dose corn peptide group, the experiment started after 1 week of adaptive feeding. The control group and CP group were fed with ordinary feed and others were fed with high-fat feed, while the control group was given intragastric administration of purified water, the CP group and the low-, medium-, high-dose corn peptide group were given intragastric administration of corn peptide(800, 400, 600 and 800 mg/(kg·d), respectively), and the puerarin positive control group was given intragastric administration of 300 mg/(kg·d) of puerarin, for 10 weeks. The body weight and general condition of rats were recorded every week, after 10 weeks, the indexes of 7 groups were compared.
Results: Compared with the model group, the liver index(3.67, 3.29, 3.19 and 3.04, P<0.05) of the rats in the three doses of corn peptide groups decreased. The homeostasis model assessment of insulin resistance(13.66, 11.82, 11.55 and 10.53, P<0.05) decreased. The serum triglyceride(TG)(0.59, 0.42, 0.34 and 0.28, P<0.05), total cholesterol(TC)(2.57, 2.10, 1.67 and 1.46, P<0.05), free fatty acid(FFA)(0.66, 0.44, 0.40 and 0.36, P<0.05), and leptin(10.64, 9.87, 9.43 and 9.05, P<0.05) decreased. The serum interleukin-6(74.61, 61.66, 51.12 and 35.68, P<0.05) and tumor necrosis factor-α(100.18, 74.13, 67.44 and 48.46, P<0.05) decreased. The serum aspartate aminotransferase(41.38, 19.41, 14.98 and 8.44, P<0.05) and alanine aminotransferase(25.14, 13.10, 11.57 and 7.48, P<0.05) activity decreased. The liver TG(9.89, 5.55, 4.73 and 3.13, P<0.05), TC(1.73, 0.97, 0.80 and 0.50, P<0.05) and FFA(1.81, 1.11, 0.77 and 0.70, P<0.05) decreased. The serum malondialdehyde(MDA)(21.36, 15.24, 12.75 and 10.87, P<0.05) level and liver MDA(11.87, 8.27, 6.33 and 4.98, P<0.05) level decreased. The serum and liver superoxide dismutase and glutathione peroxidase activity increased(P<0.05), and the effect is related to the intervention dose of corn peptide. The size of the liver became smaller, the liver color gradually changed from light yellow to light red.
Conclusion: Corn peptide has a certain preventive effect on NAFLD in rats, and the preventive effect of corn peptide is related to its intervention dose.
Keywords: corn peptide; inflammation; lipid accumulation; nonalcoholic fatty liver disease; oxidative stress.