结直肠散发性腺瘤模型建立的探讨

Establishment of Animal Model Sporadic Colorectal Adenoma

目的通过改进传统的DMH结直肠癌肿瘤模型诱导方法,建立一个高效、稳定、实用的结直肠腺瘤模型,以用于散发性腺瘤生物学行为和分子生物学机制的研究。方法选用SPF级SD雄性大鼠。诱导剂为1,2-二甲基肼(DMH)和PPAR-γ受体拮抗剂(GW9662)。PPAR-γ受体激动剂为吡格列酮。试验分四组:阴性对照组、DMH组、DMH+GW9662组、DMH+GW9662+吡格列酮组。共观察12周。试验结束取远端结直肠(全结直肠的1/2)用福尔马林4°C过夜固定,美蓝染色后实体显微镜下观察、计数息肉,并照相。全部息肉及微隆起粘膜进行组织学检查。结果阴性对照组无腺瘤发生。DMH组发现1枚腺瘤,腺瘤诱导成功率为12.5%(1/8),荷瘤数为0.125(1/8)。DMH+GW9662组发现16枚腺瘤,诱导成功率为87.5%(7/8),荷瘤数为2.0(16/8)。DMH+GW9662+吡格列酮组发现5枚腺瘤,诱导成功率为28.6%(2/7),荷瘤数为0.714(5/7)。结论DMH联合应用GW9662可以在短期内成功诱导大鼠结直肠腺瘤。该模型较单纯DMH诱导的大鼠结肠癌和畸变隐窝灶模型更具实用价值。

Objective To build an economical, effective and stable new experimental animal model of sporadic colorectal adenoma based on traditional DMH-indueed colorectal carcinoma model. The new animal model can be used to investigate the biological behavior and molecular mechanism of adenomas. Methods Male Sprague-Dawley rats were chosen in this study. Carcinogenic agent was DMH. GW9662 was chosen as the antagonist of PPAR-γ. Agonist of PPARγ was pioglitazone. Thirty-seven rats were randomly grouped into four groups, named as negative control group, group DMH, group DMH ＋ GW9662 and group DMH ＋ GW9662 ＋ Pioglitazone. The experiment period was 12 weeks. At the end of experiment, all rats were sacrificed by euthanasia. Half of the distal colorectum was taken and immersed in formalin at 4 ℃ overnight, and then recorded the polyps by anatomic microscope when stained by methylene blue. Photos 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 polyps found in negative control 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 rats. The incidence of adenoma was 87. 5 % （7/8）, and the adenoma load was 2. 0（16/8）. The incidence of adenoma and the adenoma load in Group DMH ＋ GW9662 ＋ Pioglitazone were 28. 6% （2/7） ,0. 714（5/7） respectively. Conclusion The combination of DMH and GW9662 can induce rat colorectal adenoma efficiently in a short experiment period. This animal model can be used in colorectal adenoma and pre-cancerous lesions related researches and have more advantages compared with traditional DMH induced coloreetal carcinoma model and ACF model.