Dopamine agonist pergolide prevents levodopa-induced quinoprotein formation in Parkinsonian striatum and shows quenching effects on dopamine-semiquinone generated in vitro

The neurotoxicity of dopamine (DA) quinones that appears in dopaminergic neuron-specific oxidative stress has recently been shown to play a role in the pathogenesis and/or progression of Parkinson disease. To clarify the effects of a DA agonist, pergolide, on the levodopa-induced elevation of quinones, the authors examined, striatal changes in quinoprotein using a hemi-parkinsonian mouse model. The level of striatal quinoprotein was significantly elevated specifically on the parkinsonian side, but not on the control side, after repeated levodopa administration. This levodopa-induced increase in striatal quinoprotein was almost completely suppressed by adjunctive administration with pergolide on the lesioned side. Furthermore, it was clarified that pergolide scavenged DA-semiquinones generated in vitro in a dose-dependent manner. These suppressive and quenching effects of pergolide against cytotoxic DA quinones may play a key role in its neuroprotective mechanism in the parkinsonian brain.