Metabolism of 2-acetamidofluorene in the steppe lemming

Abstract

NEW or unusual species are being investigated for the purpose of finding animals better suited than the customary mice, rats, and dogs to test chemicals for carcinogenicity. The steppe lemming (Lagarus lagarus, Pall) has been recently introduced into cancer research (Pogosianz, Bolonina and Olshevskaja, 1960).This species was found useful in studies of skin cancer induction with certain polynuclear aromatic hydrocarbons and for transplantation experiments.Recent developments with carcinogenic aromatic amine derivatives have suggested that this class of compounds requires metabolic activation by hydroxylation on the nitrogen (Boyland, Dukes and Grover, 1963;Cramer, Miller and Miller, 1960; Heringlake, Kiese, Renner and Wenz, 1960;Irving, 1964;Miller, Cramer and Miller, 1960; Uehleke, 1964). In order to investigate their potential susceptibility to such chemicals, we determined whether steppe lemmings metabolized 2-acetamidofluorene (AAF) by N-hydroxylation, a reaction performed by a sensitive but not by a resistant species Weisburger et al., 1964a). MATERIALS AND METHODSAnimals.-Two breeding pairs of steppe lemmings, provided by the Laboratory Animals Centre, Carshalton, Surrey, were raised in transparent plastic mouse cages using Sanicell and hay as bedding. The diet consisted of natural foodstuffs (apples, sweet potatoes, carrots and sunflower seeds) without need for supplementary water. Males were separated from the pregnant females before birth of the litters, usually consisting of 6-9 infants. Females and males were left apart for at least 3 to 4 weeks after parturition; otherwise further pregnancies resulted after the customary gestation period of about 20 days, but with smaller litters and poorer survival of the young.Healthy adult male (8) and female (6) lemmings were selected for the metabolism experiments during which they had free access to apples, carrots, and water.Chemicals.-Commercial 2-acetamidofluorene was recrystallized from 95 % ethanol. [9-14C]-2-Acetamidofluorene (specific activity of 2-33 X 106 c.p.m./mg. or 5-2 X 105 c.p.m./,umole), N-hydroxy-2-acetamidofluorene, and the other hydroxylated derivatives, namely 1-, 3-, 5-, 7-hydroxy-2-acetamidofluorene were prepared by published methods Weisburger and Weisburger, 1958).

Biochemical Pharmacology of the Intestinal Flora

“…These glucuronides are recovered from cthe cecums of germfree rats but are virtually absent in the cecal contents of conventional rats fed either fl uorenylacetamide (63) or N-hydroxyacetamidobiphenyl (60). The glucuro nides survive also in the cecal contents and feces of germfree but not of conventional rats after administration either of N-hydroxyfl uorenylacetamide (64).or N-hydroxy lacetamidobiphenyl (60). It is unclear, however, whether these metabolic contribu tions by the flora infl uence the carcinogenic action of these compounds.…”

N-Hydroxylation in Aminostilbene Carcinogenesis

“…Metabolites excreted in urine from rats fed AAS were fractionated into free compounds and sulphuric acid and glucosiduronic acid conjugates by alumina chromatography of ether: ethanol (3: 1 v/v) extracts of urine using the procedure of Weisburger, Grantham, Morris and Weisburger (1961). The conjugates with sulphuric acid and glucosiduronic acid were then hydrolysed with Taka diastase and f6-glucuronidase respectively and the liberated metabolites characterized by paper and thin layer chromatography.…”

Carcinogen Testing: Current Problems and New Approaches

“…The standard typical bioassays for the detection of chemical carcinogens as developed by the National Cancer Institute (NCI) requires the use of male and female rats, mice, and occasionally hamsters of strains selected for their sensitivity to carcinogens (1). The standard test involves determination of the maximally tolerated dose (MTD) of a product, after which, groups of 50 male and female animals are given the MTD and half-MTD in a 2-year test and, in some in-SCIENCE, VOL.…”

“…The elimination of unnecessary long-term testing for all chemicals by the decision point approach makes more extensive testing of suspected epigenetic agents economically feasible. Methods for conducting long-term bioassays have been reviewed 406 (1,16), and we need only emphasize here that expert judgment is required for design of the test procedures as well as for reliable evaluation and interpretation of the results.…”