Establishment of Animal Model Sporadic Colorectal Adenoma

Objective 　To build an economical, effective and stable new experimental animal model of spo2 radic colorectal adenoma based on t raditional DMH2induced colorectal carcinoma model. The new animal model can be used to investigate the biological behavior and molecular mechanism of adenomas. Methods 　Male Sprague2Dawley rat s were chosen in this study. Carcinogenic agent was DMH. GW9662 was chosen as the antagonist of PPAR2γ. Agonist of PPARγ was pioglitazone. Thirty2seven rat s were randomly grouped into four groups, named as negative cont rol group, group DMH, group DMH + GW9662 and group DMH + GW9662 + Pioglitazone. The experiment period was 12 weeks. At the end of experiment, all rat s were sacrificed by euthanasia. Half of the distal colorectum was taken and immersed in formalin at 4 ℃overnight, and then recorded the polyp s by anatomic microscope when stained by methylene blue. Pho2 tos of polyps were taken with high resolution digital camera and reversal film. All polyps and some flatten risen mucosa were verified by histology. Results 　There were no polyp s found in negative cont rol group. One adenoma was found in Group DMH. The incidence of adenoma was 12. 5 % (1/ 8), and the adenoma load was 0. 125 (1/ 8) . In Group DMH + GW9662, 16 adenomas were found in all 8 rat s. The incidence of adenoma was 87. 5 % (7/ 8), and the adenoma load was 2. 0 (16/ 8) . The incidence of adenoma and the ade2 noma load in Group DMH + GW9662 + Pioglitazone were 28. 6 % (2/ 7), 0. 714 (5/ 7) respectively. Conclu2 sion 　The combination of DMH and GW9662 can induce rat colorectal adenoma efficiently in a short ex2 periment period. This animal model can be used in colorectal adenoma and pre2cancerous lesions related researches and have more advantages compared with t raditional DMH induced colorectal carcinoma model and ACF model.