The MPTP-lesioned non-human primate models of Parkinson's disease. Past, present, and future

Non-human primate (NHP) models of Parkinson's disease (PD) have been essential in understanding the pathophysiology and neural mechanisms underlying PD. The most common toxin employed, MPTP, produces a parkinsonian phenotype in NHPs that is very similar to human PD with excellent response to dopaminergic drugs and development of long-term motor complications. Over the past 25 years, MPTP-lesioned NHP models, using several species and a variety of MPTP administration regimens, have been used to understand disease pathophysiology, investigate several stages of the disease progression, from pre-symptomatic to advanced with motor complications, and apply knowledge gained to develop potential therapeutics. Many treatments in common use in PD patients were developed on the basis of studies in the MPTP model, in particular dopamine agonists, amantadine, and targeting the subthalamic nucleus for surgical treatment of PD. Continued development of novel therapies for PD will require improving methods of evaluating symptoms in NHPs to ease translation from NHP to patients with homogenized scales and endpoints. In addition, recent studies into non-motor symptoms of PD, especially in response to chronic treatment, is expanding the usefulness and impact of MPTP-lesioned NHP models. Despite these obvious successes, limitations still exist in the model, particularly when considering underlying mechanisms of disease progression; thus, it appears difficult to reliably use acute toxin administration to replicate a chronic progressive disorder and provide consistent evidence of Lewy-like bodies.