The synaptic protein alpha-synuclein has been identified as a major component of Lewy bodies, a pathological hallmark of Parkinson's disease (PD). Prior to the formation of Lewy bodies, mislocalization and aggregation of the alpha-synuclein in brain tissue is frequently observed in various neurodegenerative diseases. Aberrant accumulation and localization of alpha-synuclein are also observed in the aging human brain, for which reason aging is regarded as a risk factor for neurodegenerative disease. To investigate changes in alpha-synuclein properties in the aging brain, we compared alpha-synuclein immunoreactivity in brain tissue of young (2-years-old) and middle-aged (6-years-old) common marmoset (Callithrix jacchus). Our analyses revealed marked changes in alpha-synuclein immunoreactivity in the olfactory bulb of common marmosets of these age cohorts. Perikaryal alpha-synuclein aggregations were formed in the olfactory bulb in middle-aged animals. We also observed signals of alpha-synuclein accumulation in hippocampus in this cohort; however, unlike in the olfactory bulb, hippocampal alpha-synuclein signals were localized in the synaptic terminals. We did not observe either of these features in younger marmosets, which suggest that aging may play a role in these phenomena.
Our results using common marmoset brain corresponded with the observation that the alpha-synuclein aggregations were first occurred from olfactory bulb in human normal aged and PD brain. Therefore, common marmoset is expected as useful model for alpha-synuclein pathology. (C) 2015 Published by Elsevier Ireland Ltd.
