Fig. 2
Selective degeneration of Tg2576 DA neurons projecting to NAc core and shell since 3 months of age. A Retrograde tracing of midbrain neurons projecting to ventral and dorsal striatum 3 weeks from the injection. Left panels: injection sites of red fluorescent beads (Retrobeads) in coronal sections of NAc shell, NAc core and dorsal striatum (green-Nissl counterstained; scale: 500 μm). Right panels: Schematic representation of the corresponding midbrain regions, with injected areas marked. B Anatomical position of retrogradely labeled TH+ neurons in the midbrain. Left panels: confocal images of retrogradely labeled DA neurons from coronal midbrain sections containing VTA and SNpc (red + green; scale: 100 μm), and inset showing TH+ cells (green) in the VTA PBP (upper panel), VTA PN (middle panel), and SNpc (bottom panel) labeled with red beads from NAc shell, core and dorsal striatum, respectively (scale: 2 μm). Right panels: schematic images of coronal midbrain sections containing VTA and SNpc (scale: 100 μm). The two VTA subnuclei and SNpc are differently colored (paranigral (PN): blue; parabrachial (PBP): green; SNpc: pink). Red dots represent the position of individual retrobeads-TH+ neurons in VTA and SNpc accumulated from three different experiments. C-D Stereological quantification of TH+ cell numbers in (C) PBP and (D) PN from 3- and 6-month-old WT and Tg2576 mice. C PBP (3 months: WT: n = 9; Tg2576: n = 11; 6 months: WT: n = 10; Tg2576: n = 10 mice. Two-way ANOVA for Genotype vs Age: Interaction: F1,36 = 0.81, p = 0.3760; Genotype: F1,36 = 26,64, p < 0.0001; Age: F1,36 = 19.85, p < 0.0001. WT 3 m vs Tg2576 3 m: Unpaired t-test **p = 0.0047; WT 6 m vs Tg2576 6 m: Unpaired t-test ***p = 0.0007; Tg2576 3 m vs Tg2576 6 m: Unpaired t-test ***p = 0.0007). D PN (3 months: WT: n = 10; Tg2576: n = 11; 6 months: WT: n = 10; Tg2576: n = 10 mice. Two-way ANOVA for Genotype vs Age: Interaction: F1,37 = 1.437, p = 0.2382; Genotype: F1,37 = 9.63, p = 0.0037; Age: F1,37 = 12.53, p = 0.0011. WT 6 m vs Tg2576 6 m: Mann-Whitney test **p = 0.0021; Tg2576 3 m vs Tg2576 6 m: Mann-Whitney test **p = 0.0048). E-F Stereological quantification of TH+ cell numbers in (E) VTA and (F) SNpc from 3- and 6-month-old WT and Tg2576 mice. E VTA (3 months: WT: n = 10; Tg2576: n = 10; 6 months: WT: n = 10; Tg2576: n = 12 mice. Two-way ANOVA for Genotype vs Age: Interaction: F1,38 = 1.868, p = 0.1797. WT 3 m vs Tg2576 3 m: Unpaired t-test: *p = 0.0466; WT 6 m vs Tg2576 6 m: Unpaired t-test: ****p < 0.0001; Tg2576 3 m vs Tg2576 6 m: Unpaired t-test: ***p = 0.0002). F SNpc (3 months: WT: n = 6; Tg2576: n = 6; 6 months: WT: n = 6; Tg2576: n = 6 mice)