All brain tissue processed for immunofluorescence (IF) was frozen with optimal cutting temperature compound on a microtome stage and sectioned/collected for ST (25 μm in thickness) and SN (40 μm in thickness) regions. Tissue sections were stored in cryoprotectant (30% sucrose, 30% ethylene glycol, and 0.5 M phosphate buffer, pH 7.2) at 20°C until selected for immunostaining. IF staining was conducted as previously described by Miller et al. (2011) (link), and all antibody dilutions were 1:500, unless stated otherwise (Miller et al., 2011 (link)). For stereology, SN sections were immunostained with anti-TH (cat. no. AB152; Merck Millipore, Burlington, MA) and anti-MAP2 (cat. no. AB5392; Abcam). For gliosis, SN and ST sections were immunostained with either anti–ionized calcium-binding adapter molecule 1 (IBA-1) (1:250; cat. no. 016-20001; Wako Chemicals USA, Inc., Richmond, VA) or anti–glial fibrillary acidic protein (GFAP) (cat. no. Z0334; Agilent Technologies, Santa Clara, CA) and anti-TH (cat. no. AB76442, Abcam). SN tissue was also immunostained with anti-TH and anti-Nurr1 (1:200, SC991; Santa Cruz Biotechnology, Dallas, TX) for mean intensity measurements of Nurr1. All secondary antibodies used for IF were Alexa Fluor 488, 555, and 647 (Thermo Fisher Scientific, Carlsbad, CA).