2.4.1 DMBA induced mammary tumors
The wistar rats aged 50 days, a single dose of DMBA is given. The first
malignant tumour can be identified after 20 to 30 days of DMBA
treatment. Palpation and comparison of a tumor’s volume to that of
prefabricated plasticine models are used to determine its weight. The
tumour weight is determined by multiplying the model weight by a formula
that accounts for the weights of plasticine and tumour tissue. The
pharmacological treatment begins once the overall tumour mass in the
animal has reached around 1 gm. The mitotic index, as well as tumour
histopathology, may provide information about the drug’s mode of
action(Nicol et al., 2004).
2.4.2 DMAB (3, 2-dimethyl-4-aminobiphenyl) induced colon
tumors: The 20 weeks of DMAB 50mg/kg s.c. injections into male F344
rats are used to induce tumour growth. As opposed to 74% of animals who
were fed a high-fat diet, only about 26-30% of animals who were fed a
low-fat diet developed colon cancer. This leads to the development of
adenomas (benign tumours) and adenocarcinomas (cancerous tumours) in the
large bowel (malignant tumors). The factors under investigation include
histology, tumour size, and tumour incidence. One of the model’s
drawbacks is that it takes many DMAB injections to cause colon cancers.
Furthermore, breast adenocarcinomas in female rats, salivary sarcomas,
squamous cell carcinomas of the ear duct and epidermis, stomach
papillomas, sarcomas and lymphomas, and urinary bladder carcinomas are
all inducible. Comparing pharmaceutical reactions becomes more difficult
as a result of this(Nicol et al., 2004).