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Role of the intestinal microflora in the formation of DNA and haemoglobin adducts in rats treated with 2-nitrofluorene and 2-aminofluorene by gavage. 1994

P T Scheepers, and D D Velders, and M J Steenwinkel, and J H van Delft, and W Driessen, and M M Stratemans, and R A Baan, and J P Koopman, and J Noordhoek, and R P Bos
Toxicology Department, University of Nijmegen, The Netherlands.

The role of the intestinal microflora in the metabolic activation of nitroarenes and arylamines was studied in female Wistar rats that received a dose of 1 mmol/kg 2-aminofluorene (2-AF) in sunflower oil by gavage. Another group received the same dose of 2-nitrofluorene (2-NF). A third group of animals was used as controls. Germfree (GF) rats, GF rats with a rat microflora (RM) and GF rats with a human microflora (HM) were treated. After treatment with 2-AF significant differences were observed in the formation of haemoglobin (Hb) adducts and DNA adducts. The 2-AF-Hb adduct level (mean +/- SD) observed in GF rats (0.57 +/- 0.13 mumol/g Hb) was considerably lower than that observed in RM rats (5.1 +/- 0.6) and in HM rats (6.2 +/- 1.3). DNA adduct levels showed the opposite pattern: levels of adducts co-migrating with deoxyguanosin-8-yl-aminofluorene (dG-C8-AF) in liver tissue were higher in GF rats (4.6 +/- 1.4 fmol/micrograms DNA) as compared to RM rats (2.6 +/- 0.04) or HM rats (2.0 +/- 0.7). In lung tissue and white blood cells a similar influence of the intestinal microflora on DNA adduct levels was observed. These results suggest that the intestinal microflora cleaves conjugates of 2-AF or N-hydroxy-2-AF, thus facilitating enterohepatic recirculation of these compounds and enhancing the formation of reactive intermediates binding to Hb. The latter is not observed for DNA adduct formation, indicating that most of these adducts have been formed after a single passage through the liver. After treatment with 2-NF, Hb and DNA adduct levels were much lower. An adduct spot was observed that was not present in rats that received 2-AF. In GF animals only very low levels of DNA adducts co-migrating with dG-C8-AF or deoxyguanosin-8-yl-acetyl-aminofluorene and no Hb adducts were observed, indicating that the metabolic activity of the microflora is an essential step in both Hb and DNA adduct formation.

UI MeSH Term Description Entries
D007422 Intestines The section of the alimentary canal from the STOMACH to the ANAL CANAL. It includes the LARGE INTESTINE and SMALL INTESTINE. Intestine
D002273 Carcinogens Substances that increase the risk of NEOPLASMS in humans or animals. Both genotoxic chemicals, which affect DNA directly, and nongenotoxic chemicals, which induce neoplasms by other mechanism, are included. Carcinogen,Oncogen,Oncogens,Tumor Initiator,Tumor Initiators,Tumor Promoter,Tumor Promoters,Initiator, Tumor,Initiators, Tumor,Promoter, Tumor,Promoters, Tumor
D004247 DNA A deoxyribonucleotide polymer that is the primary genetic material of all cells. Eukaryotic and prokaryotic organisms normally contain DNA in a double-stranded state, yet several important biological processes transiently involve single-stranded regions. DNA, which consists of a polysugar-phosphate backbone possessing projections of purines (adenine and guanine) and pyrimidines (thymine and cytosine), forms a double helix that is held together by hydrogen bonds between these purines and pyrimidines (adenine to thymine and guanine to cytosine). DNA, Double-Stranded,Deoxyribonucleic Acid,ds-DNA,DNA, Double Stranded,Double-Stranded DNA,ds DNA
D005260 Female Females
D005449 Fluorenes A family of diphenylenemethane derivatives.
D006454 Hemoglobins The oxygen-carrying proteins of ERYTHROCYTES. They are found in all vertebrates and some invertebrates. The number of globin subunits in the hemoglobin quaternary structure differs between species. Structures range from monomeric to a variety of multimeric arrangements. Eryhem,Ferrous Hemoglobin,Hemoglobin,Hemoglobin, Ferrous
D000818 Animals Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA. Animal,Metazoa,Animalia
D001419 Bacteria One of the three domains of life (the others being Eukarya and ARCHAEA), also called Eubacteria. They are unicellular prokaryotic microorganisms which generally possess rigid cell walls, multiply by cell division, and exhibit three principal forms: round or coccal, rodlike or bacillary, and spiral or spirochetal. Bacteria can be classified by their response to OXYGEN: aerobic, anaerobic, or facultatively anaerobic; by the mode by which they obtain their energy: chemotrophy (via chemical reaction) or PHOTOTROPHY (via light reaction); for chemotrophs by their source of chemical energy: CHEMOLITHOTROPHY (from inorganic compounds) or chemoorganotrophy (from organic compounds); and by their source for CARBON; NITROGEN; etc.; HETEROTROPHY (from organic sources) or AUTOTROPHY (from CARBON DIOXIDE). They can also be classified by whether or not they stain (based on the structure of their CELL WALLS) with CRYSTAL VIOLET dye: gram-negative or gram-positive. Eubacteria
D001711 Biotransformation The chemical alteration of an exogenous substance by or in a biological system. The alteration may inactivate the compound or it may result in the production of an active metabolite of an inactive parent compound. The alterations may be divided into METABOLIC DETOXICATION, PHASE I and METABOLIC DETOXICATION, PHASE II.
D017208 Rats, Wistar A strain of albino rat developed at the Wistar Institute that has spread widely at other institutions. This has markedly diluted the original strain. Wistar Rat,Rat, Wistar,Wistar Rats

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