Cellular and SN tissue protein were incubated in RIPA buffer (cat. no. R0278; Sigma-Aldrich; Merck KGaA) for 1 h, then centrifuged at 12, 000 × g for 15 min at 4°C. The extracted total proteins were eluted into EP tubes, and the concentration was measured using the bicinchoninic acid (BCA) assay (cat. no. 23225, Thermo Fisher Scientific, Inc.). Protein samples were separated on a 10% SDS-PAGE gel and transferred to polyvinylidene difluoride (PVDF) membranes (EMD Millipore). Membranes were blocked for 1 h at room temperature with 5% BSA with antibodies for tyrosine hydroxylase (TH) (1:1,000; cat. no. AB152, EMD Millipore), GPX4 (1:1,000; cat. no. ab125066, Abcam), FTH1 (1:1,000; cat. no. ab183781, Abcam) and β-tubulin (1:1,000; cat. no. 2146S, Cell Signaling Technology, Inc.) overnight at 4°C. The following day, the membranes were incubated in the presence of goat anti-rabbit secondary antibody (1:1,000; cat. no. 7074S, Cell Signaling Technology, Inc.) for 2 h at room temperature. Bands were observed with Protein Simple FluorChem E. Data were analyzed using ImageJ software (version 1.52a; National Institutes of Health).