Comparative study on the difference of obesity model induced by two kinds of high fat diet in Sprague-Dawley rats

Objective:To explore the differences of obese Sprague-Dawley (SD)rats model induced by lard oil high-fat (HF)diet or purified HF diet.Methods:SD weanling rats were randomly divided into three groups:D1 group,where rats were fed by lard oil HF diet;D2 group,where rats were fed by purified HF diet;C group,where rats were fed on chow.After 12 weeks,diet-induced obesity rats (top 33％ based on weight)were selected for further study,and the rest rats from group D1 and D2 were excluded.The food intake and weight were weighted daily and weekly,respectively.The subcutaneous,visceral and total fat contents of rats was measured by 256-row CT scan and the Lee index was calculated accordingly.The kidney,liver,testis,spleen and heart were weighted respectively.Serum leptin and insulin levels were quantified.The pathology in liver and adipose tissues were analyzed by HE staining.Oral glucose tolerance test (OGTT)was used to compare the glucose tolerance ability.Serum total cholesterol (T-CHO),high density lipoprotein (HDL-C),low density lipoprotein (LDL-C),triglyceride (TG)and inflammatory cytokines IL-6,TNF-α were detected as well.Results:After 12 weeks,the body weight,subcutaneous fat,visceral fat,total fat mass,wet weight of liver,kidney and heart,area under blood glucose curve and the levels of serum insulin,leptin,T-CHO,LDL-C,TG,IL-6 and TNF-α in group D2 were significantly increased compared to those of group C and group D1.HDL-C of group D2 was markedly lower than that in group C (P＜0.05).The visceral fat,total fat content and HDL-C in group D1 were significantly different from those of group C (P＜0.05).Steatosis and enlarged adipocyte were found in the livers of rats in group D1 and D2,and the lesions were more significant in group D2.Conclusion:Purified HF diet was more effective in inducing metabolic abnormalities,steatosis,peripheral chronic inflammation in obese SD rat models.But lard oil HF diet was more economical when only inducing visceral steatosis was required.