PET STUDIES OF FUNCTIONAL COMPENSATION IN A PRIMATE MODEL OF PARKINSONS-DISEASE

MPTP 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine is a neurotoxin that produces degeneration of nigrostriatal dopaminergic neurons and a chr onic parkinsonian condition in primates. Positron emission tomography (PET) studies of rhesus macaques at various time points following unil ateral MPTP administration demonstrated a different time course of deg eneration in the dopaminergic terminals in the putamen and in the cell bodies in the substantia nigra, consistent with other evidence of ret rograde degeneration. In addition, the substantia nigra showed a trans ient upregulation in dopaminergic function in the lesioned hemisphere indicating functional compensation. This plasticity has important impl ications for the therapeutic effects of growth factors and other. pote ntial treatments for neurodegenerative diseases.