[Effect of S-adenosyl-L-methionine on the cerebral and peripheral metabolism of L-dopa].

The repartition of [3H]L-dopa administered i.p. does not change in rats treated with S-adenosyl-L-methionine (SAM). The effect was studied on the central nervous system and at the periphery. The biosynthesis of metabolites [3H]dopamine and [3H]3-O-methyldopamine are also unchanged. On the other hand, in the kidney an accumulation of [3H]norepinephrine +[3H]normetanephrine was observed, while in the brainstem + midbrain the synthesis of these metabolites was decreased after SAM injection. The relations between these biochemical results and the pharmacological antiparkinsonian effects are discussed.