Effect of total flavonoids from Scutellaria baicalensis on dopaminergic neurons in the substantia nigra.

The aim of the present study was to investigate the effect of Scutellaria baicalensis stem-leaf total flavonoid (SSTF) on the dopaminergic neurons in the substantia nigra in a mouse model of Parkinson's disease (PD). The mouse model was established by intravenous injection of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). SSTF (5 mg/kg) was administered to the mice before or after MPTP injection, and the effects of SSTF on the behavior of the mice and the dopaminergic neurons in the substantia nigra were assessed. In addition, the level of serum malondialdehyde (MDA) was measured. Following injection of MPTP, the number of dopaminergic neurons in the substantia nigra was decreased and the neurons appeared atrophic. In addition, the level of serum MDA in the MPTP mice increased. The mean behavioral scores and the number of dopaminergic neurons in the SSTF treatment groups were significantly higher than in the MPTP group (P<0.05), and the mean serum MDA levels were significantly lower (P<0.05). Thus, SSTF improves the behaviors and the numbers of dopaminergic neurons in the substantia nigra in MPTP-induced PD in mice. These beneficial effects appear to be associated with the reduction in serum MDA.