Effects of Levetiracetam on Aggregation and Fusion of Membranes of Synaptic Vesicles in a Cell-Free Exocytosis Model

Abstract

We studied the effects of an antiepileptic drug, levetiracetam, on the processes of aggregation of synaptic vesicles (SVs) and their calcium-induced fusion with the target membranes in a cell-free model of neurosecretion. The size of SVs and their aggregates in the suspension was measured using laser-correlation spectroscopy. Fusion of the membrane structures was estimated quantitatively according to changes in the intensity of fluorescence self-quenching of the R18 probe (octadecylrhodamine B chloride). The action of levetiracetam resulted in intensification of clustering of SVs and decrease in the level of calcium-stimulated fusion of such vesicles both with the plasma membranes and with each other. Therefore, we obtained novel data on the effect of levetiracetam on regulation of the exocytosis process at stages of SV clustering and calcium-stimulated fusion of SVs with the target membranes.