Pleiotrophin is expressed by dopaminergic neurons but not by astrocytes in the adult substantia nigra pars compacta. (A) Bar graph showing the distribution of cells immunoreactive for PTN and TH in the substantia nigra pars compacta of adult normal rats: 18 ± 4% of TH-immunoreactive neurons expressed PTN (TH-PTN/total TH) and 48 ± 5% of PTN-immunoreactive cells were also TH-immunoreactive neurons (TH-PTN/total PTN). Mean ± SEM, n = 3. (B) Photomicrograph shows the double fluorescence of PTN (red) and TH (green) in adult normal rats. The white arrows indicate double-labeled cells (yellow). (C) The double fluorescence of PTN (red) and GFAP (green) indicates that astrocytes are not PTN-immunoreactive in normal rats. (D) Expression of PTN (red) and TH (green) in normal and 6-OHDA lesioned animals. The photographs were taken from the area indicated in the Paxinos and Watson atlas plate corresponding to bregma -4.80 mm (inset). Scale bars: B and C, 50 μm; D, 200 μm.