Effects of high-fat diet on the formation of colorectal adenomas in rats

Objective To investigate the effects of high-fat diet on the formation of colorectal adenomas in rats. Methods Twenty Wistar rats were evenly divided into two groups, one group were fed with common food and the other group were fed with high fat-diet. The rats of two groups were intraperitoneally injected with 1, 2-dimethyl-hydrazine (DMH) (40 mg/kg) once a week for 10 consecutive weeks. Rats with common diet and DMH were assigned to SDT group, and those with high-fat diet and DMH were assigned to HFDT group.The expression of Ki-67 was detected by immunohistochemistry and the expression of proliferating cell nuclear antigen (PCNA) and cyclooxy-genase 2 (COX2) was detected by immunofluorescence. The levels of serum triglyceride, cholesterol, insulin like growth factor-1 (IGF-1), insulin, leptin and tumor necrosis factor-α were determined by enzyme linked immunosorbent assay. Student′s t test and Mann-Whitney test were performed for statistical analysis. Results At the 18th week, the numbers of Ki-67 positive cells of SDT group and HFDT group were 24.00±1.84 and 75.17±3.17, respectively, and the difference was statistically significant (t=13.960, P<0.01). The fluorescence intensity of PCNA of SDT group and HFDT group was 213.70±21.61 and 333.30±30.44, respectively, and the difference was statistically significant (t=4.987, P<0.01). The levels of serum triglyceride of SDT group and HFDT group were (0.43±0.05) mmol/L and (1.14±0.07) mmol/L, respectively, and the difference was statistically significant (t=8.366, P<0.01). The levels of cholesterol were (3.75±0.26) pmol/L and (7.77±0.79) pmol/L, respectively, and the difference was statistically significant (t=4.851, P<0.01). Conclusion High-fat diet can promote the genesis and development of adnomas through influencing the body′s endocrine metabolism, increasing cell proliferation cycle and regulating inflammatory reaction. Key words: Colorectal adenoma; High-fat diet; Cell proliferation; Metabolism