A major metabolite of bupropion reverses motor deficits in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-treated common marmosets.

The atypical antidepressant, bupropion, causes a partial reversal of motor deficits in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-treated primates. However, its monoamine uptake blocking actions are believed to be mediated by the major metabolites, racemic (-)-(2R,3R)-2-(3-chlorophenyl-3,5,5-trimethyl-2-morphinol) (R,R-hydroxybupropion) and (+)-(2S,3S)-2-(3-chlorophenyl-3,5,5-trimethyl-2-morphinol) (S,S-hydroxybupropion). Therefore, we have evaluated the ability of enantiomers to improve locomotor activity and motor disability in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-treated common marmosets. Bupropion produced a little increase in locomotor activity and a more pronounced improvement in motor disability. The S,S-hydroxybupropion, but not the R,R-hydroxybupropion, enantiomer dose-dependently increased both locomotor activity and reversed motor disability. Combined administration of S,S-hydroxybupropion and R,R-hydroxybupropion at the same dose (analogous to the racemate) again improved motor function and to the same extent as produced by S,S-hydroxybupropion alone. The data suggest that the S,S-enantiomer of hydroxybupropion may possess potential antiparkinsonian activity.