Prominent perikaryal expression of α- and β-synuclein in neurons of dorsal root ganglion and in medullary neurons

Synucleins (syns) are a family of small, highly conserved proteins expressed predominantly in neurons. Although the normal function of syns is unknown, alpha-syn plays a pivotal role in several neurodegenerative diseases. The expression patterns of syns have been described in several studies, but much of this information was obtained before the cloning of all four members of this family of proteins and previous studies were limited to the analysis of single species. Here, we used antibodies specific for alpha-, beta-, and gamma-syn to study the patterns of expression in human, mouse, and rat nervous systems. Significant species-specific differences were detected in the expression of all three syns throughout the neuraxis. For example, gamma-syn is highly expressed in human cortex, while it is present only at low levels in mouse and rat cortex. Moreover, in contrast to previous reports that alpha- and beta-syns are normally localized predominantly at presynaptic terminals, we demonstrate that these proteins also are abundant in the perikarya of some neurons, such as in dorsal root ganglion. Intense alpha-syn immunoreactivity also was detected in the perikarya of human neurons in raphe, hypoglossal, and arcuate nuclei. These data underscore the need for additional studies to better understand the fundamental biological mechanism(s) targeting specific proteins to axonal terminals, as disruption of this process may be involved in the formation of pathological lesions. (C) 2001 Elsevier Science.