Systemic administration of 3-NP leads to a progressive expression of c-Jun in the striatum, selectively. c-Jun expression was analyzed by immunocytochemistry using a selective antibody. A, High magnification of c-Jun immunoreactivity in the Piriform cortex shows basal expression in this region in both Control and3-NP-treated rats. Note that c-Jun expression occurs in the DL part of the striatum at 3-NP-6 days treatment. B, c-Jun-immunoreactive cells were depicted in the striatum using an image analyzer. Note their appearance in the DL striatum specifically at 3-NP-6 days treatment. C, Quantification of c-Jun-immunoreactive cells was performed as in Figure 4. Statistical analysis: **p < 0.01 when comparing scores5–6 and 7–8; ***p< 0.0001 when comparing scores 7–8 and <5; ^#p < 0.05 when comparing scores 5–6 and <5(Scheffé test).