Necrosis,Cirrhosis and Cancer of Liver in Rats Fed a Diet Containing Dimethylaminoazobenzene. ∗

It was recently reported 1 that dietary liver injury (necrosis, cirrhosis) seen in rats fed a synthetic ration is determined in great part by the absence of the lipotropic activity of casein. These changes can be prevented to a large extent by the addition of casein to the diet, but this is accomplished more effectively by the combined oral administration of cystine and choline.

During the last 2 years similar investigations have been carried out with the purpose of elucidating the cause of cirrhosis and cancer of the liver in rats brought about by the addition of butter yellow (dimethylaminoazobenzene, dissolved in oil) to a diet consisting of rice and carrots, as first described by Kinosita. 2

The question arose whether or not the same mechanism that proved effective in the prevention of simple dietary liver injury 1 may also play a rôle in the prevention of changes in the liver which follow the administration of butter yellow.‡

Results. 1. In a control group of rats fed basal diet A, consisting of rice, carrots, and dimethylaminoazobenzene in oil (0.6 g per kilo of diet), supplemented with 20 μg daily each of thiamine, riboflavin and pyridoxine and with 100 μg daily of pantothenic acid, cirrhosis, atypical, nodular proliferation of bile ducts and carcinoma§ of the liver were a regular feature. In different groups the incidence of these changes fluctuated from 80 to 100%. However, only 40% of rats fed the same diet with the addition of 18% casein∥ showed similar changes. These observations are in close agreement with the results obtained by Kensler and his collaborators 4 just published.

2. Sixty rats were put on basal diet A (rice, carrots, dimethylaminoazobenzene) with the usual supplements of thiamine, riboflavin, pyridoxine and pantothenic acid. In addition sub-group 1 (16 rats) of this experiment received from 10 to 20 mg of choline daily, sub-group 2 (12 rats) received from 25 to 50 mg of cystine daily and sub-group 3 (12 rats) received daily from 25 to 50 mg of cystine plus from 10 to 20 mg of choline. Sub-group 4 (20 rats) received no supplement. The results are summarized in Table I.