Neuroprotective effects of edaravone on 6-OHDA-treated DA neurons in vitro. Left column: TH staining of DA neurons (a: non-6-OHDA-treated DA neurons) demonstrates that the number of surviving 6-OHDA-treated DA neurons significantly increased by the treatment with 10-4 and 10-3 M edaravone (e and f), compared to that with 10-6 and 10-5 M (c and d) edaravone as well as control without edaravone-administration (b). Scale bar: 30 μm. Right column: The graph demonstrates the number of surviving DA neurons by edaravone-administration. Data are shown as mean percentages of the cell number relative to the number of DA neurons without 6-OHDA-treatment +S.E. *p < 0.01 vs. 6-OHDA-treated DA neurons without edaravone-administration and those with low dose edaravone (10-6 and 10-5 M) by ANOVA.