OXIDATIVE STATUS IN SENESCENCE-ACCELERATED MICE

The lipid peroxidation and activities of antioxidant enzymes were exam ined in the livers of two substrains of senescence-accelerated mice (S AM): senescence-resistant SAM-R/1 and senescence-prone SAM-P/1. Fluore scent age pigment and conjugated diene levels in both substrains incre ased gradually with age, hut we found higher levels in SAM-P/1 at all ages tested. Differences in the levels of lipid peroxidation products became more marked with age. Among the enzymes studied, only mitochond rial superoxide dismutase (SOD) in SAM-P/1 showed decreased activity i n all age groups. The specific mitochondrial SOD in that case was Cu,Z n-SOD. The amount of Cu,Zn-SOD in mitochondrial fractions of SAM-P/1 w as only half that of SAM-R/1, whereas there were no apparent differenc es in the mRNA levels of both SAM groups. Our study indicates that imp aired transport of Cu,Zn-SOD into mitochondria after cytosolic synthes is reduces defense against oxidative stress. That reduction may he one of the factors contributing to accelerated senescence in the SAM-P/1.