These animals received an injection of AAV2-CDNF 4.0 × 107, 2.0 × 108, or 1.0 × 109 vg into their left striatum, while the right striatum was used as a control (intact, or injected with AAV2-GFP or with PBS). All rats used for the titer-dependent expression analysis were decapitated 4 weeks after AAV2 vector injection. In a pilot study, GDNF expression following

AAV2-GDNF injection was determined 9 weeks after viral vector injection (n = 3). After decapitation, the brains were removed and the SN (2-mm punch from 1-mm section) and the striatum (in total) were collected and frozen. Samples were homogenized in 150 μL of lysis buffer (137 mmol/L Inhibitors,research,lifescience,medical NaCl, 20 mmol/L Tris, pH 8.2, 1% NP40, Inhibitors,research,lifescience,medical 10% glycerol, 1 mmol/L phenylmethanesulfonylfluoride, 0.5 mmol/L NaVO3, and Complete Mini protease inhibitor cocktail [Roche, Mannheim, Germany]) using a sonicator (Rinco Ultrasonics, Romanshorn, Switzerland). The tissue samples were centrifuged at 15,300g for 20 min (4°C), 1 mol/L HCl was added to the supernatant Inhibitors,research,lifescience,medical (pH <2), and the samples were incubated 30 min on ice. The

pH of the samples was neutralized (pH 7.6) using 1 mol/L NaOH, and the samples were stored in 80°C until analysis. CDNF-ELISA Total CDNF concentration in the rat brain samples was analyzed with an in-house-built double-antibody sandwich ELISA specific for hCDNF using standard procedures. A detailed protocol for the CDNF-ELISA will be published elsewhere (E. Galli, M. Ustav, P. Taba, A. Urtti, M. Yliperttula, P. Pulkkila, and M. Saarma, unpubl. ms.). Briefly, for antigen capture, Inhibitors,research,lifescience,medical a 96-well microtiter plate

was coated with antibodies against CDNF. To reduce unspecific binding, the antibody-coated wells were incubated with 3% Calcitriol chemical structure bovine serum albumin (BSA) in PBS. After washing, homogenized brain tissue samples (or recombinant hCDNF at eight different concentrations ranging from 0–1000 pg/mL for a standard Inhibitors,research,lifescience,medical curve) were applied on the wells and incubated overnight at +4°C. The homogenized SN samples were diluted 1:4 and analyzed as duplicate. In the case of striatal samples, the control-side samples were diluted 1:4 and analyzed as triplicate, whereas the left-side AAV2-CDNF-injected samples were diluted 1:20, or in the case of lower vector titers (4.0 × 107 and 2.0 × 108 vg), samples were diluted 1:4, and analyzed as triplicate. On the following day, the plate was washed and a detection antibody against GSK-3 CDNF was added to the wells and incubated 3 h at 37°C. The detection antibody was produced in a different animal species from the coating antibody used. Finally, the formed antibody-CDNF-antibody “sandwich” complexes in the wells were visualized with a horse-radish peroxidase (HRP)-conjugated secondary antibody and 3,3′,5,5′-tetramethylbenzidine (TMB) substrate according to the manufacturer’s instructions (DuoSetELISA Development System, R&D Systems).