I am also working on the tumor models in my opinion 6-8 weeks is the perfect age for tumor induction. If you want to know why it is so.Plz let me know.

Thank you very much for your answer! And I would like to know why!

I agree 6-8 weeks would be a perfect age for tumor induction

I think the rats in the age of 6-8 weeks schould have cca 150-180 grams, isn´t it?

We use rats with a 180 grams of body weight and was fine for preventive experiments where rats were sacrificed after 11 weeks or in therapeutic regime, where rats sacrificed 17 weeks after the first DMH injection.

Why 6-8 weeks is a good time point to start this project it is important to know how you will be administering the drug. If it is via natural consumption (through water or food) you may want to start immediately after the animals are weaned. I've experienced a tremendous amount of loss of appetite after introducing drug/chemical carcinogen after diet has been established in Fisher 344 Rats. This may mean nothing to you if you are using injections but just in case.

6-8 weeks is truely the right time. I carried out mine exactly on the 7th week and it gave a high through-put via syringe injections

I would suggest you look at the syngergistic effects with cadmium. See the article cadmium and cell signaling signal transduction ( google it). You might want to look at low vit D levels. Cadmium is a mediator of the stress response and can change methylation and gene expression. Because it is a ubiquitous pollutant it may have an effect even if you are not adding it but it is wise to see its effects. By looking at effects on gene arrays one can infer its presence.

Dear Corina, my work is entirely related to the recapitulation of the human diseases in the mouse system. In my work I always use 10 to 12 week old mice. However, 6-8 weeks aged rats equivalent to the human 12.5 yrs and that is puberty period. So if you plan to administer the carcinogen at that age of 6 -8 weeks then you can expect the development of colon cancer at the ripe age. Alternatively, as we know that most of the colon cancer development is mainly predominant in the 47-70 yrs aged human , so you can administer the carcinogen little bit later stage ( say 12 -14 weeks). It takes another 12 weeks , means 24 weeks i.e. equivalent to the human 60 yrs to develop colon cancer in rat model. So if you want short term study then 12 to 14 weeks age is perfect because it exactly mimics human condition and age group mentioned above. But if you are interested to long term effect then 6 -8 weeks is perfect because it takes 40 weeks . Now it is your turn to decide.

Thank you all for your answers, I started last week with subcutaneous injections and the rats appear to be in good health. In a few months I expect to see that the colon tumors have developed. Thank you again. Regards.

Dear malay

Can you give reference to your logic. It would be beneficial for my work also

Dear Malay,

do you mean that it needs less time for colon cancer to develop in old rats than in young rats?

I am also trying to develop a new model of colorectal cancer.

Thank you very much!

Dear Shyam here is your answer.

1. You can find comparative rat and human age difference in the following paper and get more references.

A Scientific Review of Age Determination for a Laboratory Rat: How Old is

it in Comparison with Human Age? Biomedicine International Biomedicine International .2011; 2: 81-89.

2. Morphological and Molecular Alterations in 1,2 Dimethylhydrazine and azoxymethane Induced Colon Carcinogenesis in Rats.Journal of Biomedicine and Biotechnology.Volume 2011, Article ID 473964, 14 pages

Dear, Oriana. See, I did not mean such things. In either case (6-8 weeks or 12-14 weeks) it will take 12 weeks to develop neoplasm. What I wrote that is age relevancy of human and rat model. Probably you riddle with short term and long term study . Short term means : to see the effect of the drug in a short period of the experiment. In contrary , long term means: to investigate the effect of the drug over a long period (say 40 weeks). Actually, most of the drugs have their short term effects and long term residual effects. I think, right now my answer is clear to you.

thanks.

Very clear actually, as I wanted to be sure....

Thank you!

Hello Malay chaklader...Thanks..your answer is impressive and very clear for induction cancer using carcinogen in Rats.

Do you have any experience with xenograft studies?

Can you suggest something for colorectal carcinoma cell lines(like HCT116) using ectopic xenograft Nude mouse models?

Thanks,

milind

dear Corina

I think you must start your experiment on female rats with 2 years old .

in 6 weeks old rats , ovary is not matured . for starting a cancer in human . usually in women , it is in after 40 years old . a female rat in 2 years old is like that.

Do anybody has experience on Colorectal cancer induction in wistar rats with Cancer Cell lines HT 29. What precautions are required and at what age it should be started. How long it takes to develop a tumor.

Dear Corina V Sasso, Greetings. I was just looking at inducing colon cancer in rats. Most of the literature says that it can be induced in male Wistar rats. We are planning to find out why it is not induced in female rats . I found your interest in this regards. Five-six years back discussion by you, I found you could able to induce colon cancer in female rats using DMH. What is your suggestion?