Paeonolum attenuated the MPP+-induced decrease in the locomotor activity of larval zebrafish. (A) The locomotor activity was measured as the speed of control fish and fish exposed to 100 and 1000 μM of MPP+ (n = 4 groups of 15 larvae per group). (B) Locomotor activity of control, MPP+ and paeonolum-treated zebrafish larvae (n = 4 × 15). Error bars represent S.E.M. *P < 0.01.