Temporal evolution of mouse striatal gene expression following MPTP injury.

The gradual loss of striatal dopamine and dopaminergic neurons residing in the substantia nigra (SN) causes parkinsonism characterized by slow, halting movements, rigidity, and resting tremor when neuronal loss exceeds a threshold of approximately 80%. It is estimated that there is extensive compensation for several years prior to symptom onset, during which vulnerable neurons asynchronously die. Recent evidence would argue that much of the compensatory response of the nigrostriatal system is multimodal including both pre-synaptic and striatal mechanisms. Although parkinsonism may have multiple causes, the classic syndrome, Parkinson's disease (PD), is frequently modeled in small animals by repeated administration of the selective neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). Because the MPTP model of PD recapitulates many of the known behavioral and pathological features of human PD, we asked whether the striatal cells of mice treated with MPTP in a semi-chronic paradigm enact a transcriptional program that would help elucidate the response to dopamine denervation. Our findings reveal a time-dependent dysregulation in the striatum of a set of genes whose products may impact both the viability and ability to communicate of dopamine neurons in the SN.