Determination of N7- and O 6 -methylguanine in Rat Liver DNA after Oral Exposure to Hydrazine by Use of Immunochemical and Electrochemical Detection Methods

Authors: van Delft J.H.M.¹; Steenwinkel M.J.S.T.¹; de Groot A.J.L.²; van Zeeland A.A.²; Eberle-Adamkiewicz G.³; Rajewsky M.F.³; Thomale J.³; Baan R.A.¹

Source: Fundamental and Applied Toxicology, Volume 35, Number 1, January 1997 , pp. 131-137(7)

Publisher: Academic Press

Abstract:

Hydrazine belongs to a group of compounds for which there is evidence that the in vivo genotoxic effects become manifest only upon exposure to toxic dose levels. The present study was performed to investigate whether this phenomenon is also reflected in the pattern of DNA methylation. The induction of N7- and O 6 -methylguanine (MeGua) was studied in liver DNA of rats, 16 hr after treatment with various doses of hydrazine. After DNA isolation, the presence of N7-MeGua in DNA was assessed with an immunochemical method and with a physicochemical technique (HPLC with electrochemical detection). Application of these two methods resulted in almost identical patterns of dose-dependent induction of guanine N7-methylation in rats dosed orally with 0.1 to 10 mg hydrazine per kilogram of body weight, increasing from 1.1-1.3 to 39-45 N7-MeGua per 10 6 nucleotides. At lower dosages a constant adduct level was observed, equivalent to that in untreated rats (background level). The O 6 -MeGua level was analyzed by a combination of HPLC separation and competitive radioimmunoassay. A background level was observed for untreated rats and no increase was visible up to the 0.2 mg/kg dose group. After hydrazine doses from 0.2 to 10 mg/kg, O 6 -MeGua increased from 0.29 to 134 per 10 9 nucleotides. These data show that even at dosages below the maximum tolerated dose (0.6 mg/kg/day), for which carcinogenic effects have not been described, DNA adducts are formed. A comparison is made of the data obtained in this study with models that describe the mechanism of hydrazine-induced DNA methylation.

Language: English

Document Type: Research article

Affiliations: 1: Department of Molecular Toxicology, TNO Nutrition and Food Research Institute, Zeist, 3700 AJ, The Netherlands 2: MGC-Department of Radiation Genetics and Chemical Mutagenesis, Leiden University, Wassenaarseweg 72, Leiden, 2333 AL, The Netherlands 3: Institute of Cell Biology (Cancer Research), University of Essen, Medical School, Hufelandstrase 55, Essen, D-45122, Germany

Publication date: 1997-01-01

• In this: publication
• By this: publisher
• In this Subject: Ecology ,  Toxicology
• By this author: van Delft J.H.M. ;  Steenwinkel M.J.S.T. ;  de Groot A.J.L. ;  van Zeeland A.A. ;  Eberle-Adamkiewicz G. ;  Rajewsky M.F. ;  Thomale J. ;  Baan R.A.

Website © Publishing Technology. Article copyright remains with the publisher, society or author(s) as specified within the article.

• Terms and conditions
• Privacy policy
• Information for advertisers