POSSIBLE RELATIONSHIP BETWEEN CHANGES IN [H-3]DA UPTAKE AND AUTOXIDATION IN RAT STRIATAL SLICES

Many recent studies have suggested that oxidative damage is an importa nt factor in several neurodegenerative disorders. Our investigations c onsidered whether autoxidation of rat striatal slices modified dopamin e uptake. Biochemical assays (TBARS, MDA-TBA complex, aldehydes, and f luorescent lipid-soluble products) and a [H-3]DA uptake assay were per formed on nonincubated striatal slices and on slices incubated for 150 min at 37 degrees C in Krebs-Ringer buffer without addition of free-r adical generators. The results showed that spontaneous lipid peroxidat ion occured during incubation and that DA uptake kinetic was biphasic (high-affinity uptake(1) and low-affinity uptake(2)) with a significan t decrease of maximal velocity of uptake. Ascorbate, a known antioxida nt, was used to determine whether a relationship existed between lipid peroxidation and reduced dopamine uptake. Addition of ascorbate (100 and 500 mu M) in Krebs-Ringer buffer for 150 min at 37 degrees C faile d to indicate whether decreased [H-3]DA uptake resulted from lipid per oxidation. In fact, ascorbate acted as a prooxidant, only preventing d ecreased DA uptake(2) at 100 mu M. Trolox, another antioxidant, inhibi ted lipid peroxidation by about 95% with a concentration of 700 mu M a nd protected only uptake(1). With a concentration of 5000 mu M, Trolox also protected uptake(2). On the whole, these results indicate that s pontaneous autoxidation in rat striatal slices was associated with a l ipid peroxidation process that altered the DA uptake system, (C) 1998 Academic Press.