Biochemical changes related to aging in the senescence-accelerated mouse.

Several biochemical parameters reflecting the degree of senescence were compared between senile-prone (P) and resistant (R) strains of male senescence-accelerated mouse (SAM) at 11 to 12 months of age. Plasma testosterone in SAM-P amounted to half the concentration in SAM-R. In the liver and brain of SAM-P, the content of malondialdehyde (MDA) and the activity of monoamine oxidase B (MAO-B) were significantly higher than those in SAM-R. Moreover, large amounts of fluorescent lipofuscin were detected in the SAM-P liver. Compared with SAM-R, both membrane and cytosolic fractions from the SAM-P liver contained small amounts of protein and showed less activity of superoxide dismutase (SOD). The present findings suggest that the male SAM-P rapidly acquires biochemical changes which are considered to be part of the normal aging process.