SYNAPTOPHYSIN-IMMUNO POSITIVE GRAINS ASSOCIATED WITH AMYL OID PLAQUES IN CEREBRUM STRUCTURES OF 5XFAD MICE

Alzheimer's disease (AD) is one of the most common forms of dementia worldwide. A key histopathological feature of AD is the extracellular deposition of beta-amyloid plaques. In AD patients, the development of cognitive impairment is more closely associated with synaptic loss. In this regard, studying the mechanisms behind the synaptic dysfunction and identifying ways of AD correction is relevant. It should be noted, that synaptophysin is one of the main markers of synapses, which is localized in the membranes of presynaptic vesicles. The aim of the study is to morphologically assess the distribution of synaptophysin protein in brain structures of 5xFAD transgenic mice in the presence of amyloid accumulations. Transgenic line of 5xFAD mice (n = 3) was used in the present study. An immunohistochemical staining to synaptophysin with additional alcian blue colouring was carried out to identify synaptic terminals and amyloid clusters in the cortex and hippocampal formation. Clusters of intensely stained synaptophysin-immunopositive grains surrounding the amyloid plaques were detected in the hippocampal formation and cortex. The most pronounced amyloidosis with abnormal distribution of synaptophysin-immunopositive structures has been observed in the subiculum, CA1 region of the hippocampus and the inner (ganglionic and polymorphic) layers of the cortex by morphometric analysis. A positive linear dependence between the area of synaptophysin-immunopositive grains and the size of amyloid plaques in different regions of the hippocampal formation and cortex has been established by regression analyses. The intense accumulation of synaptophysin-immunopositive grains surrounding the amyloid plaques suggest a functional dependence between the progression of amyloid pathology and synaptic dysfunction.

synaptophysin, Alzheimer’s disease, 5xFAD, amyloid plaques, cerebrum