Immunohistochemical Revealing of Alpha-Synuclein in Synaptic Contact Area of Hippocampal CA₃ Zone

The aim of this research was to study the localization of alpha-synuclein in hippocampal structures of rat brain in normal condition. Material and methods. As a material for the study, hippocampus of adult male Wistar rats (n=10) with absence of verified neurodegeneration signs was used. The material obtained was fixed in zinc-ethanol-formaldehyde, a fixative providing high preservation of antigenic determinants. The detection of alpha-synuclein was carried out using the immunohistochemistry method. Results. In the study intensive diffuse staining of hippocampal CA₃ zone neuropilewas revealed, with predominant distribution of alpha-synuclein in stratum lucidum and stratum radiatum, which are rich in synaptic contacts of the mossy fibers of dentate gyrus. Alpha-synuclein is presented in the form of cluster of granules that have mainly rounded shape and linear size of 1.6±0.5 µm. Also a positive reaction to alpha-synuclein was detected in the pyramidal layer of CA₁ and CA₃ zones in the form of cytoplasmic granules (inclusions). It is noted that in the CA₁ zone the number of detected granules is much larger than in CA₃ zone. Conclusion. Normally, the localization of alpha-synuclein-immunopositive granules corresponds to stratum lucidum and stratum radiatum of hippocampal CA₃ zone, being an integral part of presynaptic endings of mossy fibers of dentate gyrus. In addition to terminal endings, alpha-synuclein is detected in the pyramidal neurons bodies of the CA₁ and CA₃ zones of the hippocampus. Further study of this protein in both normal and pathological conditions, as well as the development of human neurodegenerative diseases models on laboratory animals, will provide the understanding of prospects of alpha-synuclein as a marker of the synaptic state of mossy fibers and the development of structural and functional changes in them.

альфа-синуклеин, гиппокамп, CA₃ зона, мшистые волокна зубчатой фасции, synuclein alpha, hippocampus, CA₃ zone, mossy fibers synapse

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