Gumenyuk V. The influence of cholesterol on the fusion of homo-and heterotypic membranes of nerve terminals

Objects of research - cell-free model systems that reproduce the steps of exocytosis: aggregation of synaptic vesicles and calcium-stimulated fusion of synaptic vesicles with the target membranes and the secretion of neurotransmitter glutamate from synaptosomes of rat brain. Objective: To investigate the course of the individual steps of exocytosis - synaptic vesicle docking and thier fusion with the target membranes, depending on the level of cholesterol in the membrane structures of synaptosomes. Methods: preparative biochemistry, spectrophotometry, spectrofluorimetry, laser correlation spectroscopy, electron and confocal microscopy, as well as statistical analysis. In cell-free system was shown that treatment of synaptic vesicle suspension by methyl-cyclodextrin (MCD) does not alter their aggregation process in the medium containing cytosolic fraction of synaptosomes. There is the first experimental proof of the feasibility of using of the fluorescent probe R18 for the registration of stimulated fusion process between synaptic vesicles with different target membranes. At the same time, extraction of cholesterol from the synaptic vesicle or plasma membranes synaptosomes reduces their calcium-dependent fusion process. It was obtained that the MCD-reduced cholesterol level of the synaptic vesicle membranes did not affected the ability of antiepileptic drugs to activate the fusion of homotypic membranes. It was found that at experimental pathologies like D3-vitamin deficiencies and diabetes type 1 the cholesterol concentration in the plasma membranes of neurons was increased.