Parkinson's disease is characterized by the selective death of dopaminergic neurons in the midbrain and accumulation of amyloid fibrils composed of α-synuclein (αSyn). Current treatment involves approaches that compensate the death of dopaminergic neurons by increasing the dopamine levels in remaining cells. However, dopamine can interact with αSyn and produce oligomeric species which were reported to be toxic in many models. We studied formation of dopamine-induced αSyn oligomers and their effect on the αSyn aggregation. Using the Thioflavin T kinetic assay, we have shown that small oligomers efficiently inhibit αSyn fibrillization by binding to fibril ends and blocking the elongation. Moreover, all the fractions of oligomer species proved to be nontoxic in the differentiated SH-SY5Y cell model and showed negligible neurotoxicity on isolated rat synaptosomes. The observed inhibition is an important insight in understanding of dopamine-enhancing therapy on Parkinson's disease progression and explains the absence of pathology enhancement.

Department of Biochemistry and Biotechnology Vasyl Stefanyk Precarpathian National University 57 Shevchenko Str Ivano Frankivsk 76018 Ukraine

Department of Neurochemistry Palladin Institute of Biochemistry National Academy of Sciences of Ukraine 9 Leontovycha Street Kyiv 01054 Ukraine

Laboratory of Chemical Biology Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences Flemingovo náměstí 542 2 160 00 Prague 6 Czech Republic

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