Figure 4.

Anterograde transport of glial-derived neurotrophic factor (GDNF) from putamen to substantia nigra. A representative histological section at the level of the midbrain is shown in an nonhuman primates (NHP) that received bilateral putamenal adeno-associated virus serotype 2 (AAV2)-GDNF. GDNF expression (brown) primarily occurs in the area of substantia nigra reticulata (SNr), with minimal overlap into substantia nigra compacta (SNc) identified by tyrosine hydroxylase expression (blue). The box in a is shown at greater magnification in b, and the box in b is shown at greater magnification in c. Arrowheads in c identify neurons in SNr that express GDNF. VTA, ventral tegmental area.