Fig. 4. Immunofluorescent expression of PPAR-α in the dopaminergic nigrostriatal circuit. (A–C) Red PPAR-α-labeled cellular nuclei are mainly located in the substantia nigra pars reticulata (SNr), and the ventral tier of the substantia nigra pars compacta (SNc) where they overlap with green TH+ dopamine neurons (white arrows). The inbox in C shows a magnified image of PPAR-α-labeled neurons in the ventral tier of the substantia nigra. Many neurons inside the red nucleus (R) express PPAR-α, and this signal is nearly absent in the ventral tegmental area (VTA). (D–H) Red PPAR-α-labeled cells are located widespread in the striatum (Str) surrounded by green TH+ fibers. The receptors PPAR-α are mostly observed with a nuclear localization (white arrows). Note red PPAR-α-ir inside fiber bundles of the internal capsule crossing the striatum. (I) Magnified image of PPAR-α-labeled neurons in the substantia nigra showing that receptors mostly show a nuclear distribution but there is also cytoplasmic expression (yellow cytoplasmic signal). Abbrev.: PPAR-α, peroxisome proliferator-activated receptor α; R, red nucleus; SNc, substantia nigra pars compacta; SNr, substantia nigra pars reticulata; Str, striatum; TH, tyrosine-hydroxylase; VTA, ventral tegmental area.