Changes in salsolinol production and salsolinol synthase activity in Parkinson's disease model

Salsolinol is an endogenous neurotoxin derived from dopamine, and has been proved to cause the apoptosis of the dopaminergic neurons involved in the pathogenesis of Parkinson's disease (PD). Salsolinol synthase is the key enzyme in the biosynthesis of salsolinol, and its activity exists in most regions of rat brain. However, the activity distribution and its catalyzed function in vivo are still unknown. On the basis of the chromatographic assay established previously, we investigated the activity of salsolinol synthase and salsolinol production in both cell and rat model of PD induced by 6-hydroxydopamine (6-OHDA). The results show that the enzymatic activity increases in cell model and in the striatum region of PD rat brain. Nevertheless, there is a reduction of activity in hippocampus, cortex, and midbrain of PD model when compared with control. Conversely, the level of salsolinol was significantly increased in the midbrain region. Together, these results indicate the relationship between the oxidative stress induced by 6-OHDA and the activity of salsolinol synthase, suggesting the correlation of the endogenous neurotoxin and Parkinson's disease. Further research will provide more evidence and clarity on the function of Sal synthase.