CHROMOSOME-ABERRATIONS INDUCED IN MICE BY CHRONIC FEEDING OF 2-AMINO-3,4-DIMETHYLIMIDAZO[4,5-F]QUINOLINE (MEIQ)

Dietary intake of mutagenic compounds is considered to be an important factor for the induction of some human cancers. Highly mutagenic comp ounds are known to be formed in meat during the cooking process. Since the discovery of such compounds, many studies have been conducted to evaluate their carcinogenic potential. One of the most mutagenic compo unds formed in the cooking of meat is 2-amino-3,4-dimethylimidazo[4,5- f]quinoline (MeIQ). The recent development of mouse chromosome paintin g probes expand the capability of evaluating these food mutagens as po tential clastogens in vivo. In this paper, we demonstrate the inductio n of chromosome aberrations in mice chronically exposed to MeIQ in the ir diet. CDF1 female mice were fed 400 ppm MeIQ beginning at 7 wk of a ge. At 76 wk of age, five control and eight exposed mice were euthaniz ed. Blood and bone marrow cells were obtained and arrested in metaphas e. Whole chromosome painting probes were used for fluorescence its sit u hybridization of metaphase cells from blood and bone marrow. MeIQ-ex posed mice were found to have a twofold increase in translocations and a 16-fold increase in fragments in their peripheral blood compared wi th controls. No aberrations were observed in the bone marrow. All orga ns were examined for the presence of tumours and routine histopatholog ical analysis was performed on all organs as well as any tissue with m acroscopic ab;normalities. Forestomach and/or liver tumours developed in all but one of the mice fed MeIQ, but no such tumours were observed in the control mice. These data indicate that MeIQ is clastogenic and carcinogenic in vivo. (C) 1998 Published by Elsevier Science Ltd. All rights reserved.