TRPC1 Protects Dopaminergic SH-SY5Y Cells from MPP+, Salsolinol, and N-methyl-(R)-salsolinol-induced Cytotoxicity

Neurotoxins and alterations in Ca2+ homeostasis have been associated with Parkinson's disease (PD), but the role of store-operated Ca2+ entry channels is not well understood. Previous studies have shown the neurotoxicity of salsolinol and 1-methyl-4-phenylpyridinium ion on SH-SY5Y cells and cytoprotection induced by transient receptor potential protein 1 (TRPC1). In the present study, N-methyl-(R)-salsolinol was tested for its cellular toxicity and effects on TRPC1 expression. MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assays, DAPI (4',6-diamidino-2-phenylindole), fluorescein isothiocyanate-Annexin-V/propidium iodide, western blot analysis, and JC-1 labeling revealed that the three indicated drugs could induce caspase-dependent, mitochondrial-mediated apoptosis. Exposure of SH-SY5Y cells to the indicated drugs resulted in a significant decrease in thapsigargin-mediated Ca2+ influx and TRPC1 expression. Immunocytochemistry experiments revealed that neurotoxins treatment induced TRPC1 translocation to the cytoplasm. Taken together, our results indicate that treatment with neurotoxins may alter Ca2+ homeostasis and induce mitochondrial-mediated caspase-dependent cytotoxicity, an important characteristic of PD.