A. M. Petrov1, K. E. Kudryashova, Yu. G. Odnoshivkina, and A. L. Zefirov
Kazan Medical State University, Kazan, Russia
Received August 2, 2010
Abstract—In this study, using neuromusclar preparations of frog cutaneous pectoris muscle and mouse dia-
phragm we have shown that the membranes of nerve terminals (NT) contain nearly two times more cholesterol
than the plasma membrane of muscle fibers. Using the fluorescent B subunit of cholera toxin (CT-B), we iden-
tified the areas in the NT membranes with high concentrations of GM1 ganglioside, the marker molecule for
cholesterol- and sphingolipid-enriched membrane microdomains, so-called lipid rafts. Intense fluorescent spots
appear in the NT when lipid rafts were identified during high-frequency stimulation, which cause massive exo-
cytosis of synaptic vesicles followed by endocytosis. The double staining of neuromusclar preparations with
CT-B and FM1-43, a dye that is taken up into synaptic vesicles during endocytosis, has demonstrated good cola-
beling by these dyes. This indicates the presence of large amounts of cholesterol and lipid rafts in membranes
of synaptic vesicles. Thus, cholesterol is present in NT membranes at the high concentration required for the
organization of lipid rafts, which are common in the plasma membranes of the NT and the membranes of syn-
aptic vesicles. The role of cholesterol and lipid rafts in the processes of exo- and endocytosis is discussed.
Keywords: cholesterol, ganglioside GM1, lipid rafts, synaptic vesicles, active zone, motor nerve terminals
DOI: 10.1134/S1819712411010089
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