Objective: To establish nonalcoholic fatty liver disease (NAFLD) in young rats, and to investigate the metabolic characteristics of these rats.
Methods: Fifteen male and fifteen female SD rats of 3 weeks old were randomly divided into three groups, normal group (N), 20% high fat group (HF1) and 30% high fat group (HF2). All the rats were fed under Specific pathogen Free (SPF) condition for 6 weeks and executed at the end of the 6th week. Body length and weight of each rat as well as their liver weight were measured for calculating Liver Index (LI). ALT, AST, TG, TC, INS, Glu and HOMA-IR in the blood were measured. Liver tissue homogenate was prepared for detecting TG level. The liver section was stained with HE and oil red. The expression of SPEBP-1 and leptin in liver was detected by immunostaining.
Results: The typical pathological change of NAFLD was found in the rats of HF groups. In HF2 group, no rats died during the experiment and the degree of fat degeneration is homogeneous. Comparing with those in N group, TC (mmol/L), liver TG (mmol/L) and ALT levels in HF2 group were significantly elevated (2.50+/-0.39 vs 1.82+/-0.43, P less than 0.01; 25.38+/-13.29 vs 12.09+/-9.59, P less than 0.01 and 69.80+/-18.22 vs 48.00+/-10.45, P less than 0.01, respectively). Comparing with those in N group, TG level in HF1 group was significantly decreased (0.17+/-0.10 vs 0.32+/-0.12, P less than 0.05), Glu level in HF1 group was significantly elevated (12.33+/-3.48 vs 8.13+/-2.53, P less than 0.05). There were no significant difference between the results of AST, INS and HOMA-IR among the groups. The expression level of SREBP-1 and leptin increased in HF groups.
Conclusion: NAFLD can be induced by 30% high-fat feeding for 6 weeks in young rats, high-fat feeding induces the expression of SREBP-1 and leptin expression and fat synthesis.