Expression of alpha‐synuclein (AS) in autonomic neurons is increased in Parkinson's disease (PD)

Background and objective We have previously shown that expression of the main protein constituent of Lewy bodies, AS, is detectable in autonomic neurons in a subset of the adult population. The objective was to determine wheteher expression has greater prevalence or intensity in PD than in the general population or patients with Alzheimer's disease (AD) Methods Archival autopsy samples of colon obtained from adult patients with pathologically confirmed PD, AD, or no neurological disease were immunostained with anti AS antibody KM51 diluted 1:70 and visualized with a MACH 3 polymer kit. The expression was scored as absent (AS‐), or present (AS+) in perikarya or terminals, semiquantitevely rated 1 to 3. Results Just over ½ of 70 subjects with no neurological disease were AS+: neither prevalence nor intensity varied by age over 40 years. Differences between sexes were not significative (NS). All 10 PD patients were AS+ as compared to 25 of 54 age‐matched subjects (p< 0.002). The average intensity was also significantly greater (p< 0.002). In contrast 3 of 8 AD cases were AS+ (NS as compared with normal population) Conclusion AS+ in autonomic neurons is common in the adult population. This trait is significantly more prevalent and intense in PD, but not in AD. Either the development of PD increases AS expression, or PD preferentially develops in AS+ subjects