Patients with Parkinson’s disease (PD) express motor symptoms only after 60-80% depletion of striatal dopamine (DA). Before this symptomatic phasis, the progressive loss of the dopaminergic innervation is likely associated with adaptive biochemical modifications within the striatum (the main target of this projection). These modifications could be involved in delaying the appearance of motor symptoms. We propose that our MPTP monkey model, based on a progressive intoxication (injection of 0,4 mg/kg, every 4 or 5 days; see Mounayar, et al. SfN abstract 2005), is suitable to study the compensatory mechanisms which underlie the presymptomatic stage of PD. Microdialysis has been performed in the same awake animal during normal state, during full expression of motor symptoms induced by MPTP and after recovery of these symptoms in order to correlate motor deficits and their recovery with changes of striatal neurotransmitter levels. We focussed our study on DA and its metabolites (DOPAC, HVA), GABA, Glutamate (Gl...