Synaptic vesicle cycle, dendritic spines and signal transduction

Abstract

In the nervous system, the synapse is the structure that allows a neuron pass an electrical or chemicalsignal to another neuron or another cell (muscle or glandular). The word synapse comes from "synaptein"that Sir Charles Scott Sherrington and his colleagues minted from the Greek "syn" (together) and "haptein"(buckling). Most part of the synaptic transmission is performed through chemical synapses. Chemicalsynapses have a slower response than the electric ones; they have the advantage of amplifying thesignal generated through a cascade of second messengers. Chemical synapses can be excitatory orinhibitory and are characterized by a presynaptic terminal (where there are vesicles that contain theneurotransmitters) in contact with a postsynaptic terminal (where there are the ionotropic and metabotropicreceptors) separated by the synaptic cleft. Synapses can occur on axons (axo-axonal), on dendrites (axodendritic), on soma (axo-somatic) and on dendritic spines. Dendritic spines are small profusions withthe function of synaptic compartmentalization. There is much information about classic neurotransmitters,such as acetylcholine, glutamate, GABA, glycine, dopamine, norepinephrine, and serotonin, but the studyof new neurotransmitter (i. e., ATP, nitric oxide, endocannabinoids, and neuropeptides) has advancedenormously. This review is a collection summary of key information from the recent literature describingthe molecular and functional aspects of the cycle of synaptic vesicle, the composition of postsynapticdensity, dendritic spines, and signal transduction.