Effect of dietary restriction and age on the formation of DNA adducts fromthe mouse liver microsome-mediated metabolism of 2-nitropyrene

N-(Deoxyguanosin-8-yl)-2-aminopyrene and N-(deoxyadenosin-8-yl)2-aminopyren e were formed from metabolism of 2-nitropyrene (2-NP) in vitro and in vivo. The effects of dietary restriction (DR) and age on the formation of these DNA adducts were studied. In the presence of calf thymus DNA, [G-H-3]2-NP w as metabolized by liver microsomes of 5-, 9-, and 12-month old male B6C3F(1 ) mice fed ad libitum (AL microsomes) or by liver microsomes of 5-, 9-, and 12-month old male B6C3F(1) mice fed a restricted diet (DR microsomes). In all cases, both adducts were detected. The total quantities formed from 5-, 9-, and 12-month AL microsomes, and 5-, 9-, and 12-month DR microsomes wer e 5.58+/-1.78, 8.79+/-2.32, 3.57+/-0.34, 1.63+/-0.40, 5.46+/-0.21, and 4.15 +/-0.94 pmol 2-NP/mg DNA, respectively. These results suggest the effect of DR on DNA adduct formation may be age dependent. However, the ratio of dG/ dA adduct formation was similar in all cases and was independent of age and caloric intake of the mice used for the microsomal preparations.