Fig. 11

Western blotting of α-synuclein oligomeric species in the substantia nigra pars compacta (SN), frontal cortex area 8 (FC), and putamen (Put) in total homogenate cytosolic (Cyt), deoxycholate (Dxc), and sodium dodecyl sulphate (SDS) fractions in middle-aged individuals (MA) and Parkinson’s disease stages 5–6 (PD). α-synuclein oligomeric species are only observed in the three fractions in PD but not in MA cases, thus indicating abnormal α-synuclein solubility and aggregation of α-synuclein in the substantia nigra and frontal cortex in PD. However, the patterns of α-synuclein oligomers differ in the three regions. Two net bands of 50 kDa and about 100 kDa are seen in the three fractions in the substantia nigra, but three bands with a considerable smear of about 30 kDa, 50 kDa, and 90 kDa are found, mainly in the cytosolic and deoxycholate fractions, in the frontal cortex. In addition, note the higher density of α-synuclein bands in the frontal cortex when compared with the substantia nigra in PD. No α-synuclein oligomers are detected in the putamen, whereas a band of about 17 kDa is found in MA and PD cases