Effect of short-term [acutely symptomatic (n = 5), black bars], long-term [chronically symptomatic (n = 5), white bars], and low-dose [asymptomatic (n = 5), cross-hatched bars] MPTP exposure on striatal PPT mRNA levels as measured by in situ hybridization histochemistry at three rostrocaudal levels [rostral (A), mid (B), and caudal (C)]. At all rostrocaudal levels similar decreases in PPT gene expression are evident in symptomatic groups compared with both controls (*p < 0.01 vs normal controls; Δp < 0.05 vs normal controls) and the asymptomatic group (^∧p < 0.01 vs asymptomatic group; #p < 0.05 vs asymptomatic group). No significant decreases from control are seen in the asymptomatic group. CD, Caudate nucleus;DL, dorsolateral; DM, dorsomedial;N ACC, nucleus accumbens; VL, ventrolateral; VM, ventromedial.