Abstract
The flavonoid tilianin is derived from the leaves of Dracocephalum moldavica L. amiales and has been proven to serve a neuroprotective role in cerebral ischemia. Therefore, the aim of the present study was to determine whether tilianin could prevent oxidative stress and the apoptosis of dopaminergic neurons in Parkinson's disease (PD). The dopaminergic neuron MES23.5 cell line was treated with 1-methyl-4-phenylpyridinium (MPP+) to construct a PD cell model. Following pretreatment with tilianin, the Cell Counting Kit-8 assay was used to assess cell viability. The protein and mRNA expression levels of tyrosine hydroxylase were determined using immunofluorescence, reverse transcription-quantitative PCR (RT-qPCR) and western blotting. mRNA and protein expression levels of inflammatory cytokines IL-6, IL-1β and TNF-α and oxidative stress-related enzymes manganese superoxide dismutase and catalase were also quantified using RT-qPCR and western blotting, respectively. Cell apoptotic rate was analyzed using the TUNEL assay and the expressions of apoptosis-related proteins Bcl-2, Bax and cleaved caspase-3 were detected by western blotting. MAPK signaling pathway-related protein expression levels were assessed via western blotting in MPP+-stimulated MES23.5 cells with or without tilianin pretreatment. Tilianin was demonstrated to exert no cytotoxic effects on MES23.5 cells and was able to prevent MPP+-induced reductions in cell viability. Pretreatment with tilianin also inhibited MPP+-induced inflammatory cytokine secretion, oxidative stress and apoptosis of MES23.5 cells. In addition, the protein expression levels of MAPK signaling pathway-related proteins were upregulated by MPP+, whereas pretreatment with tilianin downregulated these in a dose-dependent manner. The results of the present study indicated that tilianin may exert anti-inflammatory and antioxidant effects and inhibit the MAPK signaling pathway, which may ameliorate injury to dopaminergic neurons induced by PD.