Inhibition of 2-amino-3-methylimidazo[4,5-ƒ]quinoline-DNA adduct formation in CDF 1 mice by heat-altered derivatives of linoleic acid

Abstract

Grilled ground beef contains a number of carcinogens, including aminoimidazoazaarenes, such as 2-amino-3-methylimidazo[4,5-ƒ]quinoline (IQ), as well as anticarcinogenic substances, such as heat-generated derivatives of linoleic acid (CLA). In the present study, CLA was administered by gavage every other day to young adult CDF 1 mice for a period of 45 days (50 μl/48 hr for days 1–24 and 100 μl/48 hr for days 25–45), using trioctanoin as a control. On day 46 all animals received a single oral dose (50 mg/kg) of IQ and tissues were collected 24 hr later. Tissue DNA was purified and analysed for IQ-DNA adducts by 32P-postlabelling assays. Compared with controls, CLA treatment caused a 43.1 and 31.8% inhibition of adduct formation in the livers of male and female mice, respectively. In the lung and large intestine CLA had a 74.2 and 39.4% inhibitory effect, respectively, in the female only, whereas there was no effect in the stomach or small intestine of either sex. In the kidneys of females, CLA treatment inhibited IQ-DNA adduct formation almost completely (95.2%), whereas in the kidneys of males CLA had no effect. It is concluded that CLA inhibits IQ-DNA adduct formation in certain IQ target organs (liver and lung) and non-target organs (large intestine, kidney), but is inactive in other target organs (stomach) and non-target organs (small intestine) of the CDF 1 mouse.