Salviae miltiorrhizae Radix inhibits superoxide generation by activated rat microglias and mimics the action of amphetamine on in vitro rat striatal dopamine release

Salviae miltiorrhizae Radix (SMR), an eminent herb in the treatment of cardiovascular disorder ( called blood stasis in traditional Chinese medicine), is widely used in China, Japan, Taiwan and Korea. SMR is also herbal medicines used in the treatment of drug addiction without scientific support for their mechanism of action. We evaluated the effect of SMR on superoxide production by rat microglias using a 2-methyl-6-(p-methoxyphenyl)-3,7- dihydroimidazo[ 1,2-a] pyrazin-3-one-dependent chemiluminescence assay. SMR dose-dependently inhibited superoxide production by microglias stimulated with phorbol myristate acetate or opsonized zymosan, while it had no effect on superoxide production by a hypoxanthine-xanthine oxidase system. These results indicate that SMR does not have a scavenging effect, but has an inhibitory effect on superoxide generation by microglias. Although SMR is commonly used for treating chronic cerebral infarction, it may also have a protective effect on progression of Parkinson's disease or Alzheimer's disease. On the other hand, the present study investigated the effect of the medicinal plant on dopaminergic neurotransmission in comparison with amphetamine. The effect of crude water extracts (0.1 g/ml) of SMR on K+ ( 20 mM)-stimulated dopamine release from rat striatal slices was compared with amphetamine ( 10(-4) M) using high-performance liquid chromatography with electrochemical detection to measure endogenous dopamine. Amphetamine and SMR significantly increased K+-stimulated dopamine release (P< 0.001) from rat striatal slices when compared with K+-stimulated alone. SMR potentiated the effect of amphetamine on K+-stimulated dopamine release ( P< 0.001) when compared with amphetamine alone. The results indicate that SMR may stimulate dopamine release in the same manner as amphetamine. It remains to be determined whether the effect of this extract on dopamine function is important in its therapeutic use in the treatment of drug addiction.