Pleiotrophin over-expression was induced after the lesion to mimic more closely a possible use in patients. Schematic illustration of the experimental design. Rats were injected with Adβgal or AdPTN in the substantia nigra seven days after being injected with 6-OHDA or vehicle in the striatum. The animals were sacrificed 14 days after adenoviral injections (21 days after 6-OHDA injection). Histology and immunohistochemistry were performed on free-floating coronal serial tissue sections of the entire striatum and substantia nigra. Beta-galactosidase activity was detected using X-gal as substrate (A). Pleiotrophin (B) and TH (C and D) were revealed with DAB as chromogen. The microphotographs were taken from sections of 6-OHDA lesioned rats treated with Adβgal (A and D) or AdPTN (B and C).