Behavioral test

To evaluate motor dysfunction, a forelimb use asymmetry test (the cylinder test) was used⁵². In short, 14 days after injection of 6-OHDA, animals were placed in a quiet, well-lit room at least half an hour in advance. Then, the rats were placed in a clean, open-top plexiglass cylinder (diameter: 20 cm, height: 30 cm). The behavior was recorded for 5 min for each session. Three observers who were blind to the treatment scored the numbers that the animal used the left and the right forelimbs to touch the cylindrical walls.

Apomorphine-induced circling test was used to reflect DA denervation in rodents with unilateral nigrostriatal lesion^50,52. In brief, 14 days after surgery, rats were injected intraperitoneally with apomorphine (M8750 Sigma, 5 mg/kg) and placed in a clean open arena (120 × 120 cm). The whole experiment was performed in a quiet, well-lit room. Thirty minutes after the injection, the rats were recorded for 10 min. The number of rotations towards the contralateral side of lesion was counted.