Increased synphilin-1 expression in human elderly brains with substantia nigra Marinesco bodies

The aim of the present study was to examine the expression of synphilin-1, alpha-synuclein, and tyrosine hydroxylase in human elderly brains and the incidence of Marinesco bodies (MBs, intranuclear inclusions) in the neuromelanin-containing substantia nigra neurons. The brains of twenty-two individuals without clinical signs and symptoms of parkinsonism and dementia and an additional two parkinsonian patients were dissected and subjected to histopathological examination and western blotting. Ubiquitin-positive and agr;-synuclein-negative MBs were found in 0.84-9.45% of the nigral neurons from brains of 15 healthy individuals and both parkinsonian patients. The frequency of pigmented nigral neurons containing MBs was positively correlated with age. The levels of tyrosine hydroxylase in the caudate nucleus and putamen decreased with age, and were inversely correlated with the MB frequency. The level of synphilin-1 in the caudate nucleus was positively correlated both with age and the MBs. Additionally, the MB appearance was correlated with synphilin-1 level in the substantia nigra. No significant correlation between alpha-synuclein expression and age or MBs was found. Our results suggest that synphilin-1 expression increases with aging. Further studies on expression of this protein in elderly brains are warranted.