Background: Parkinson's disease (PD) is a neurodegenerative disorder characterized by loss of dopaminergic neurons in the substantia nigra. The purpose of this study was to examine neuroprotective effects of Hepad S1, an herbal medicine used for the treatment of PD, in in vitro and in vivo models of PD.
Methods: Differentiated neuronal PC12 cells underwent a cytotoxicity assay and oxidative stress analysis including DCF-DA staining, glutathione, and malondialdehyde, after exposure to 1-methyl-4-phenylpyridium (MPP+). Male Sprague-Dawley rats were used as 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced PD models. After 4-week oral administration of Hepad S1 (200, 300, 400, and 500 mg/kg/day), the levels of complex enzyme I activity and dopamine, and dopaminergic neuronal cell number in substantia nigra were measured by enzyme linked immune-sorbent assay (ELISA) and microscopic observation, respectively. Circulating serotonin and orexin A were also examined by ELISA.
Results: Hepad S1 pretreatment prevented the ability of MPP+ challenge to decrease glutathione and increase lipid peroxidation in cells, indicating antioxidant activity. Hepad S1 recovered MPTP-induced decreases in complex I enzyme activity and enhanced dopamine availability in substantia nigra. Serum levels of serotonin and orexin A were increased by Hepad S1 treatment in model animals. Hepad S1 treatment was associated with the preservation of tyrosine hydroxylase-positive cells in the substantia nigra of MPTP-treated rats.
Conclusions: Hepad S1 exerts antioxidant and neuroprotective effects on neurons of the substantia nigra in a rodent model of PD.
Keywords: Hepad; Korean medicine; Parkinson’s disease; dopamine; reactive oxygen species.