Assessing neuroprotection in Parkinson's disease: from the animal models to molecular neuroimaging in vivo

An important goal in Parkinson's Disease research is to identify neuroprotective therapy, and the interaction between basic science and clinical research is needed to discover drugs that can slow or halt the disorder progression. At present there is not a perfect animal model of PD to test neuroprotective strategies, however the models that portray the basic characteristics needed are toxin-induced and gene-based models. The first group comprehends 6-OHDA e MPTP and recently rotenone, paraquat and epoxomicin treated animals that shows some of human disease characteristics. Gene-based models are various and, even if with limits, they seem suitable models to test neuroprotection in PD since they present replicable lesions, a predictable pattern of neurodegeneration and a well-characterized behavior, biochemistry and morphology to assist in the understanding of induced changes. In clinical trials researchers have first used as marker of disease progression clinical scores and motor tasks which are limited by the potential symptomatic effect of tested drugs and are not useful in the pre-clinical phases of PD. Recently has emerged the important role of neuroimaging (Dopamine Transporter SPECT, 18FDopa-PET) as surrogate biomarker of PD progression. Even if there are still concerns about the influence of regulatory effects of tested drugs, neuroimaging features could represent a good outcome measure to evaluate PD progression and putative neuroprotective effect of pharmacological and non-pharmacological manipulations.