[Modeling mechanism] There are two ideal animal carcinogenic chemicals: N-butyl-N-(4-hydroxybutane 1). -Nitrosamines, BBN) and N*methyl-N-nitrosourea (N-methyl-N-nitrosourea, MNU) are representative nitroso compounds and N-[4-(5 -Nitro-2-furyl)-2, -thiazolyl]carboxamide (N-[4-(5-nitro-2-furyl)-2-thiazolyl]carboxamide, FANFF) is representative Nitrofuran compounds. Bladder cancer lesions are usually multiple, and FANFT-induced bladder cancer starts from the basement membrane and gradually invades various tissues, from mild hyperplasia to invasive cancer, and finally leads to distant metastasis. Under the electron microscope, cancer cells are randomly arranged and have different sizes and shapes. They are round, irregular and spindle-shaped, with large nuclei, increased euchromatin, clustered edges, and nucleoli usually adjacent to the nuclear envelope.
[Modeling method]
1. About 250 g of F344 male rats were selected and fed with 0.2% FANFT feed to develop bladder cancer in newly weaned rats. If such rats take FANFF for the rest of their lives, or need 25 to 36 weeks, they will be randomly assigned to control their diet. The mouse died of bladder cancer 20 months ago.
2, N-butyl-N-(3-carboxypropyl)nitrosamine, another metabolite of BBN, is excreted in the urine and comes into contact with the urothelium, causing cancer. Low-dose multiple administration by gavage has a higher tumor induction rate. Intraperitoneal injection can also be used to induce animal models of bladder cancer. The induction rate of cancer is similar to that of tube feeding, but acute animal poisoning and adhesive intestinal obstruction are more likely to occur. FANFF is usually mixed with animals for consumption, usually at a concentration of 0.02%. MNU is a direct carcinogen and requires bladder perfusion. This may cause animal urinary tract diseases, secondary urinary tract infections and bladder stones.
[Characteristics of the model] All rats have bladder proliferative damage within 2 weeks after FANFT intake, and FANFT intake for 8 weeks will increase proliferative damage, resulting in nodular and papillary damage, especially nodular damage. The bladder cavity gradually enlarged. When the rat survives long enough, it penetrates the muscle layer and invades the surrounding tissues. The carcinogenic effects of bladder cancer can be divided into two stages. FANFT can be used as an early carcinogen. This model is useful for studying possible early and late carcinogens. [Model Evaluation and Application] Bladder cancer is one of the most common malignant tumors in the urinary system. Inducing bladder tumors in animals is an effective way to study the etiology, pathology and prevention of human bladder cancer. Like human primary carcinogenesis, the development of rat bladder cancer has undergone three important morphological stages: epithelial hyperplasia, papilloma formation and canceration. The carcinogenic dose and duration of action are positively correlated with the cancer cycle.