Gangliosides and synaptic transmission.

Several physiologically relevant findings are reported indicating a functional involvement of gangliosides (sialoglycolipids) in the process of neuronal transmission: a) changes of gangliosides in both concentration and composition during developmental maturation of the CNS and with the level of phylogenetic organization; b) metabolic variations of gangliosides in relation to sensory stimulations; c) involvement of gangliosides in the process of thermal adaptations; d) correlations between long-lasting compensatory changes in the composition of brain gangliosides and long-term changes in the bio-electrical activity of the CNS and the learning ability; e) pronounced ability of gangliosides to complex with Ca2+-ions. On the basis of these experimental data an actualized hypothesis on the molecular interaction of brain gangliosides in the process of synaptic transmission is presented. The main feature of this hypothesis is the assumption that when the negatively charged sialic acids of gangliosides form complexes with Ca2+-ions (cluster-formation) these parts of the synaptic membrane become rigid. Dissociation of the Ca2+-ganglioside-complexes induces an "opening" of the presynaptic zone of interactions by means of an increase of membraneous fluidity, together with Ca2+-influx thus enabling fusion of vesicles and release of transmitter.