GPI-1046 protects against loss of striatal TH and promotes regeneration of striatal dopaminergic markers in MPTP-treated mice. (A) Dose dependency of GPI-1046-mediated recovery of striatal TH innervation density in the concurrent MPTP-GPI-1046 model. Quantitative analysis of striatal TH levels was as described. At all dose levels, TH innervation density was significantly greater than MPTP/vehicle-treated cases alone (Student’s t test, P < 0.001). (B) The dose-dependent recovery of TH+ labeled punctae is evident in the striata of MPTP-lesioned mice treated after an 8-day delay with s.c. GPI-1046 at 4, 10, 20, or 40 mg/kg. Quantitation of the post-MPTP-administered GPI-1046 in regeneration of striatal TH innervation density is depicted graphically. At all dose levels, TH innervation density was significantly greater than MPTP treated cases alone (Student’s t test, P < 0.001).