δ-Opioid Receptor Activation Inhibits Ferroptosis by Activating the Nrf2 Pathway in MPTP-Induced Parkinson Disease Models

Figure 4

DOR reduced MPTP-induced dopaminergic neuronal degeneration in striatum. (a) Representative immunofluorescence images of TH-positive cells in the striatum of the four groups; (b) quantitative analysis of TH-positive regions in the striatum in the groups (n = 5). The quantitative analysis of the TH-positive regions was performed using ImageJ. All statistical differences were tested using a t-test. Data are expressed as the mean ± SEM (n = 5/group). The significance is expressed as ^## vs. control group. vs. MPTP group. ns, not significant vs. MPTP group. DOR, δ-opioid receptor; MPTP, 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine; PD, Parkinson disease; DADLE, [d-Ala², d-Leu⁵]-enkephalin; ns, not significant.

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