Age-dependent change in activities of lysosomal enzymes in rat brain.

The age-dependent change in activities of seven lysosomal enzymes (cathepsin D, beta-glucuronidase, acid phosphatase, acid/alkaline DNases and acid/alkaline RNases) was studied in four brain regions (cerebrum, hippocampus, pons and cerebellum) of Wistar rats. The activity of cathepsin D was significantly increased with aging in the four regions. The age-dependent change in activities of acid and alkaline DNases showed the characteristic regional difference, and the ratio of acid to alkaline DNases was increased with aging in all regions. Acid RNase showed the lowest activity in 18-month-old rats, and alkaline RNase activity was decreased with aging. The activity of beta-glucuronidase was higher in 2-month-old rats in all of the regions studied. Acid phosphatase showed no significant age-dependent change except in pons. The study demonstrated that all of the lysosomal enzyme activities do not change in parallel with aging, and that the age-dependent change showed the characteristic regional difference.