Mammary Cancer Induced by a Single Dose of Polynuclear Hydrocarbons

Enhancement and inhibition of the induction by 7,12-dimethylbenz(a)anthracene of mammary tumours in female Sprague-Dawley rats

“…The influence of such factors cannot be excluded from the experiments of Dao (1964) and Wattenberg and Leong (1967 The most interesting outcome of the experiments is the degree to which stimulation and inhibition of the metabolism of DMBA can influence mammary tumour induction by a near-critical dose level (2.5 mg.) of the carcinogen. (The rats used in this study appear considerably less sensitive to mammary tumour induction than those used by Huggins, Morii and Grand (1961) who found that 2-5 mg. DMBA intravenously induced tumours in every rat.) In contrast to the results with 2.5 mg. DMBA, the less significant differences between the groups given 5-0 mg. DMBA demonstrate that, with higher dose levels of carcinogen, it becomes increasingly more difficult to affect tumour induction by stimulating or inhibiting the metabolism of the carcinogen (cf.…”

“…The Huggins method of producing tumours in rats (Huggins, Grand and Brillantes, 1961;Huggins, Morii and Grand, 1961) has proved useful for studying the effects of interference with the metabolism of DMBA on tumour induction. The administration of the carcinogen as a single dose obviates the difficulties encountered in attempting to influence the rate of metabolism of carcinogens which require chronic administration, as in previous experiments of, for example, Richardsoni, EXPLANATION OF PLATE.…”

“…Stein and Borsos-Nachtnebel (1952), Meechan, McCafferty and Jones (1953) and Miller, Miller, Brown and MacDonald (1958). Furthermore, by choosing the intravenous route of administration of DMBA (Huggins, Morii and Grand, 1961) in preference to the intragastric route in the present experiments, rats were exposed systemically and immediately to known amounts of DMBA at accurately selected times after pretreatment, thereby eliminating possible effects of pretreatment drugs on absorption and metabolism of DMBA by the gut mucosa. The influence of such factors cannot be excluded from the experiments of Dao (1964) and Wattenberg and Leong (1967 The most interesting outcome of the experiments is the degree to which stimulation and inhibition of the metabolism of DMBA can influence mammary tumour induction by a near-critical dose level (2.5 mg.) of the carcinogen.…”

Azo dyes prevent hydrocarbon-induced leukemia in the rat.

“…We investigated the influence of sequence of administration (protector/challenger or challenger/protector) on the incidence of leukemia. Two groups of female rats were given a set of four Two methods are available in the rat for the rapid screening of compounds that will prevent hydrocarbon-induced cancer: (i) the prevention of adrenal apoplexy (6,11), and (ii) protection of the rat from fatal toxicity from massive doses of hydrocarbons as described in the present study.…”

Identification of four trans-3,4-dihydrodiol metabolites of 7,12-dimethylbenz[a]anthracene and their in vitro DNA-binding activities upon further metabolism.

“…7,12-Dimethylbenz[a]anthracene (7,) is a potent inducer of mammary cancer (1) and causes adrenal apoplexy and massive necrosis in the two inner zones of the adrenal cortex (2) in rats. It is also known to be a transplacental carcinogen in rats (3), an inducer of hepatomas in mice (4) and nephroblastomas in ovariectomized rats (5), and a potent skin carcinogen in mice (6,7).…”