Spatial organization of quantum transmitter release and the role of cytoskeleton

Abstract

Nowadays, basic features of the processes of chemical excitatory transmission between the neurons are well described by the quantum transmitter release theory. One of the fundamental statements of this theory is the following: the processes of transmitter release in central and peripheral neurons are spatially limited and occur in specialized presynaptic formations, active zones (AZ), where the contents of synaptic vesicles are released by exocytosis [1-4]. Such spatial limitation of the neurotransmitter secretion processes by the borders of AZ is related to the need to ensure a maximum efficiency of synaptic transmission. The aim of our research was to identify possible factors and presynaptic mechanisms responsible for such specialized spatial organization of the exocytotic processes within single AZ by using an electrophysiological technique, which allowed us to describe the topography of quantum secretion from motor nerve endings (NE). electrodes with smelted tips (diameter, 0.5-1.0 ~tm; resistance, 0.5-2.0 M~). Microelectrode tips were positioned on the NE in a triangular manner so that the distance between them was about 3-8 ~tm (Fig. 1A). Mutual disposition of the nerve terminal and microelectrodes was sketched. MEPC were recorded in the norm and alter colchicine applications (5 9 10 -3 mM). Signals recorded by each of the microelectrodes were amplified and measured using a computer-aided system. Then, the coordinates of quantum transmission release plots were determined based on correlation of the signal amplitudes recorded by each electrode and calculated with the use of a special program. It was suggested that the locus of signal generation on the postsynaptic membrane and the locus of transmitter release responsible for MEPC production spatially coincide [5]. The graphs, which reflect the disposition of quantum release in the NE, were plotted after processing of 200-5,500 MEPC signals. Statistical data processing was performed with the use of Origin 5.0 and Excel-2000,