Senescence-associated decrease of NADPH-induced lipid peroxidation in rat liver microsomes

Senescence is associated with decrease in the NADPH-induced lipid peroxidation in liver homogenate as well as rough and smooth microsomes of female rats. In the microsomal fractions, sensitivity to NADPH-induced lipid peroxidation is high in young adults (3-month-old), decreases in middle aged (12-month-old) and reaches lowest levels in senescent (30-month-old) rats. Increasing the concentration of co-factors or time of incubation does not alter this resistance observed in the senescent rats. Major factors responsible for this resistance in senescent rats seem to be low levels of substrate in the c reductase, cytochrome P-450 and high cholesterol:phospholipid ratios besides enhanced levels of superoxide dismutase, alpha-tocopherol and reduced glutathione.