MPTP-induced loss of TH-positive SNpc neurons. (A–C) In saline-treated control mice, there was no difference in the number of TH-positive SNpc neurons among the genotypes DAT-Cre (A), Retlx (B), and DAT-Retlx/lx (C). (D–I) In addition, MPTP-induced depletion of TH-positive SNpc neurons did not differ among the genotypes DAT-Cre (D and G), Retlx (E and H), and DAT-Retlx/lx (F and I) at 14 days (D–F) and 90 days (G–I). Furthermore, there was no difference between 14 and 90 days for each of the three genotypes.