THE EFFECT OF A LONG-TERM (6 MONTHS) TREATMENT WITH (-)DEPRENYL ON ANTIOXIDANT ENZYME-ACTIVITIES IN SELECTIVE BRAIN-REGIONS IN OLD FEMALE FISCHER-344 RATS

The effect of long term treatment with (-)deprenyl (s.c. injection three times a week for 6 months) on superoxide dismutase (SOD) and catalase (CAT) in selective brain regions was examined in old (22 months) female Fischer 344 rats. The three doses of deprenyl used (0.1, 0.25 and 0.5 mg/kg/ day) increased the activities of both enzymes in substantia nigra, striatum and cerebral cortices essentially in a dose dependent manner. However, for CAT activities in cerebral cortices, the smallest dose of 0.1 mg/kg/day was most effective, while the highest dose (0.5 mg/kg/day) had no effect. In contrast to these brain regions, there were no significant differences in enzyme activities between control and deprenyl-treated groups in the hippocampus and cerebellum. If the effect of deprenyl on the life span of female F-344 rats is causally related to its effect on antioxidant enzyme activities in selective brain regions as shown in this study, then a dose of 0.25 or 0.5 mg/kg/day appears to be most appropriate. Since this dose is much lower than the dose suggested by our previous short term (3 week) experiments, an even longer term experiment is necessary to determine the optimal dose of deprenyl to increase free radical scavenging and thus possibly extend lifespan.