Age- and duration-dependent effects of MPTP on cortical serotonin systems

► MPTP produced decreases in striatal DA which partially recovered 18 months later. ► By contrast, striatal 5-HT was increased 18 months after MPTP treatment. ► In the cortex, decreases in NE were transient but those in 5-HT were long-lasting. ► Only striatal DA and NE exhibited age-related vulnerability to MPTP. ► 5-HT neurons lack the plasticity exhibited by DA neurons to MPTP toxicity.