Although 0.2 mg/ml of MPTP is much lower than the
concentration used in previous reports in zebrafish (5–45 mg/ml)
(McKinley et al., 2005; Wen et al., 2008; Bretaud et al., 2004), even
lower concentration of MPTP (0.02 mg/ml) showed the reduction
in both the number of TH+ neurons and the spontaneous
movement (Fig. 5A–D). The group treated with 0.02 mg/ml of
MPTP exhibited the intermediate phenotype between the control
and the group treated with 0.2 mg/ml of MPTP, suggesting the
dose–response relationship.