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Selective coexpression of synaptic proteins, α‐synuclein, cysteine string protein‐α, synaptophysin, synaptotagmin‐1, and synaptobrevin‐2 in vesicular acetylcholine transporter‐immunoreactive axons in the guinea pig ileum
Author(s) -
Sharrad Dale F.,
Gai WeiPing,
Brookes Simon J.H.
Publication year - 2013
Publication title -
journal of comparative neurology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.855
H-Index - 209
eISSN - 1096-9861
pISSN - 0021-9967
DOI - 10.1002/cne.23296
Subject(s) - synaptophysin , vesicular acetylcholine transporter , synaptotagmin 1 , biology , synaptic vesicle , synaptobrevin , cholinergic , neuroscience , microbiology and biotechnology , choline acetyltransferase , immunohistochemistry , biochemistry , immunology , vesicle , membrane
Parkinson's disease is a neurodegenerative disorder characterized by Lewy bodies and neurites composed mainly of the presynaptic protein α‐synuclein. Frequently, Lewy bodies and neurites are identified in the gut of Parkinson's disease patients and may underlie associated gastrointestinal dysfunctions. We recently reported selective expression of α‐synuclein in the axons of cholinergic neurons in the guinea pig and human distal gut; however, it is not clear whether α‐synuclein expression varies along the gut, nor how closely expression is associated with other synaptic proteins. We used multiple‐labeling immunohistochemistry to quantify which neurons in the guinea pig ileum expressed α‐synuclein, cysteine string protein‐α (CSPα), synaptophysin, synaptotagmin‐1, or synaptobrevin‐2 in their axons. Among the 10 neurochemically defined axonal populations, a significantly greater proportion of vesicular acetylcholine transporter‐immunoreactive (VAChT‐IR) varicosities (80% ± 1.7%, n = 4, P < 0.001) contained α‐synuclein immunoreactivity, and a significantly greater proportion of α‐synuclein‐IR axons also contained VAChT immunoreactivity (78% ± 1.3%, n = 4) compared with any of the other nine populations ( P < 0.001). Among synaptophysin‐, synaptotagmin‐1‐, synaptobrevin‐2‐, and CSPα‐IR varicosities, 98% ± 0.7%, 96% ± 0.7%, 88% ± 1.6%, and 85% ± 2.9% (n = 4) contained α‐synuclein immunoreactivity, respectively. Among α‐synuclein‐IR varicosities, 96% ± 0.9%, 99% ± 0.6%, 83% ± 1.9%, and 87% ± 2.3% (n = 4) contained synaptophysin‐, synaptotagmin‐1‐, synaptobrevin‐2‐, and CSPα immunoreactivity, respectively. We report a close association between the expression of α‐synuclein and the expression of other synaptic proteins in cholinergic axons in the guinea pig ileum. Selective expression of α‐synuclein may relate to the neurotransmitter system utilized and predispose cholinergic enteric neurons to degeneration in Parkinson's disease. J. Comp. Neurol. 521:2523–2537, 2013. © 2013 Wiley Periodicals, Inc.