A single injection of 100 micrograms of estradiol benzoate into newborn rats was followed after weaning by dietary treatment with one of two dosages of the carcinogen N-hydroxy-N-2-fluorenylacetamide. Autopsies 26 weeks later showed a higher incidence of liver cancer in male and, particularly, female rats injected with hormone than in controls. The weights of livers were greater but gonads were smaller in size in the estradiol groups. Endocrine and possibly centralnervous-system factors may play roles in formation of liver tumors.
ATTENTION to the mastomys [Rattus natalensis, Praomis natalensis (Davis, 1965;Snell and Stewart, 1967), multimammate mouse (Oettle, 1961)] as a useful species for investigations on the etiology of cancer was drawn first by the late Dr. Oettle (1955Oettle ( , 1957 who observed that older mastomys exhibited spontaneous gastric adenocarcinoma. These findings were confirmed by others, notably by Snell (1965). Additionally Oettle et al. (1959) noted that old animals infected with cercariae of Schistosoma mansoni had hepatoma.N-Hydroxy-N-2-fluorenylacetamide (N-OH-FAA) is an active metabolic intermediate derived from the well-known carcinogen N-2-fluorenylacetamide (2-acetamidofluorene, FAA). When fed to rats, in addition to the numerous tissues normally affected such as liver, mammary gland, ear duct, N-OH-FAA also gives neoplasms in the forestomach of rats (Miller et al., 1961). It seemed of interest, therefore, to examine whether the propensity of the mastomys towards carcinoma of the glandular stomach could be enhanced and this difficulty induced tumour obtained reliably and more quickly by feeding N-OH-FAA to this species. The present report deals with the results obtained. At the same time, the capability of mastomys to metabolise aromatic amine derivatives such as FAA to the active N-hydroxy derivatives was studied.
MATERIALS AND METHODS
Treatment of animalsWeanling male and female mastomys were obtained from the Animal Production Section of the National Institutes of Health. They were maintained in groups of 5 or singly in stainless steel screen-bottom hanging cages with free access to diet and water. In preliminary experiments it was found that mastomys refused to eat and did poorly on a semi-synthetic diet (see Shirasu et al., 1966) with or without carcinogen. Mastomys grew well on ground Purina laboratory chow. Toxicity tests determined that mastomys were more tolerant to N-OH-FAA than rats. Thus, definitive tests were set up at 2 dose levels, 0-06 per cent and 0 1 per cent of finely powdered N-OH-FAA, incorporated into ground Purina laboratory chow.A total of 72 male and female mastomys were divided into a control group and groups receiving 0 06 and 0 1 per cent N-OH-FAA. The animals were weighed
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.