Surgery
All surgery was performed under aseptic conditions under isoflurane anaesthesia (5% in O2 for induction, ~2% in O2 for maintenance) in a stereotaxic frame with the nose bar set at -2.3 mm. For the AAV surgery, all rats received a dual intra-nigral injection unilaterally in the substantia nigra (at the coordinates AP -4.8 & -5.8, ML +2.0 and DV -7.2). The AAV vector titre was 1.67 x 1010 vg/µL for surgeries. Infusions were carried out at a rate of 0.5 µL/min with a total volume of 3 µL per site (2 sites per rat), and a further 5 min were then allowed for diffusion. For the FN075 surgery, all rats received four intra-striatal injections unilaterally into the striatum of FN075 (4 x 1.9 µg; 4 µl of 1 mM) or its vehicle (100 µM imidazole in PBS + 0.5% DMSO); at the coordinates AP +1.3, ML +2.7; AP +0.4, ML +3.1; AP-0.4, ML +4.3; AP -1.3, ML +4.7 (from bregma) and DV -5.0 below dura. Infusions were carried out at a rate of 1 µL/min with a total volume of 4 µL per site (4 sites per rat), and a further 2 min were then allowed for diffusion.