In recent years, it has been accepted that oxidative stress is critically involved in the etiopathology of Parkinson's disease (PD) and as a result new therapeutic targets for reduction of oxidant injury and neuroprotection can be defined. Here we discuss the potential use of the transcription factor nuclear factor erythroid-2-related factor 2 (Nrf2), as a pharmacological target for neuroprotective therapy in PD. Data generated by various groups indicate that Nrf2 induces the expression of a group of cytoprotective, antixenobiotic and antioxidant enzymes that include heme oxygenase-1, NAD(P)H:quinone oxidoreductase and enzymes of glutathione (GSH) metabolism such as γ -glutamyl cysteine ligase, GSH transferases and so on. Two strategies are known to increase Nrf2 transcriptional activity in PD: i) use of certain catechol-derived quinones for selective inhibition of the Nrf2 repressor Kelch-like ECH-associated protein to increase of Nrf2 protein levels; and ii) use of glycogen synthase kinase 3 β inhibitors to maintain high protein and activity levels of Nrf2 in the nucleus. This review provides a rationale for drug design of appropriate molecules that might endorse a neuroprotective strategy to PD on the basis of attenuation of oxidative stress.

The existence of endogenous neural progenitors in the nigrostriatal system could represent a powerful tool for restorative therapies in Parkinson's disease. Sox-2 is a transcription factor expressed in pluripotent and adult stem cells, including neural progenitors. In the adult brain Sox-2 is expressed in the neurogenic niches. There is also widespread expression of Sox-2 in other brain regions, although the neurogenic potential outside the niches is uncertain. Here, we analyzed the presence of Sox-2+ cells in the adult primate (Macaca fascicularis) brain in naïve animals (N = 3) and in animals exposed to systemic administration of 1-methyl-4-phenyl-1,2,3,6 tetrahydropyridine to render them parkinsonian (N = 8). Animals received bromodeoxyuridine (100 mg/kg once a day during five consecutive days) to label proliferating cells and their progeny. Using confocal and electron microscopy we analyzed the Sox-2+ cell population in the nigrostriatal system and investigated changes in the number, proliferation and neurogenic potential of Sox-2+ cells, in control conditions and at two time points after MPTP administration. We found Sox-2+ cells with self-renewal capacity in both the striatum and the substantia nigra. Importantly, only in the striatum Sox-2+ was expressed in some calretinin+ neurons. MPTP administration led to an increase in the proliferation of striatal Sox-2+ cells and to an acute, concomitant decrease in the percentage of Sox-2+/calretinin+ neurons, which recovered by 18 months. Given their potential capacity to differentiate into neurons and their responsiveness to dopamine neurotoxic insults, striatal Sox-2+ cells represent good candidates to harness endogenous repair mechanisms for regenerative approaches in Parkinson's disease.