Molecular aspects of synaptic transmission

Authors

  • Ana C. Polli Lopes Departamento de Patologia, Faculdade de Medicina de Ribeirão Preto da Universidade de São Paulo - FMRP/USP
  • Luciana Casaletti Rosa Departamento de Morfologia, Faculdade de Medicina de Ribeirão Preto da Universidade de São Paulo - FMRP/USP
  • René de O. Beleboni Departamento de Bioquímica da Faculdade de Medicina de Ribeirão Preto da Universidade de São Paulo -FMRP/USP
  • Rodrigo N. R. Pereira Departamento de Fisiologia da Faculdade de Medicina de Ribeirão Preto da Universidade de São Paulo - FMRP/USP
  • Carlos A. C. de Vasconcelos Departamento de Patologia da Faculdade de Medicina de Ribeirão Preto da Universidade de São Paulo -FMRP/USP
  • Jorge E. Moreira Departamento de Morfologia da Faculdade de Medicina de Ribeirão Preto da Universidade de São Paulo -FMRP/USP

DOI:

https://doi.org/10.11606/issn.2176-7262.v32i2p167-188

Keywords:

Synapses. Synaptic Vesicles. Synaptic Transmission. Long-Term Potentiation.

Abstract

The Central Nervous System produces our conscious state out of various externa inputs in a continuous stream of information and storing a lifetime of memories, while keeping track of the concentration of our internal fluids and the work of muscles and glands. Synaptic transmission is the key process of all that activity. Billions of neurons communicate with each other via thousands of synapses, each of which is independently regulated. From that complexity, instead of chaos, arises the pristine order of information processed by the brain. The secretion of neurotransmitters at the synaptic active zone is the primary event of interneuronal communication. This process is regulated by a highly orchestrated cycle of membrane trafficking within the presynaptic nerve terminal. Neurotransmitters are stored in synaptic vesicles. Depolarization of the nerve terminal by an action potential results in the opening of voltage-gated Ca 2+ channels. The resulting influx of calcium ions triggers exocytosis which is a rapid fusion of the vesicles with the plasma membrane, releasing neurotransmitters into the synaptic cleft. Exocytosis involves the linking of intrinsic membrane proteins of the vesicle and the plasma membranes by specific docking and fusion, the SNARE proteins, at the active zone. The vesicle membranes are rapidly retrieved by endocytosis and the synaptic vesicles recycled within the nerve terminal. The nerve terminal is thus an autonomous unit that contains all elements required for synaptic vesicle exocytosis and proteins responsible for neurotransmitter biosynthesis and vesicular uptake. Once the neurotransmitter have been released, diffuses across the synaptic cleft and combines with receptor molecules in the membrane of the postsynaptic neuron producing, in a fraction millisecond, a large transient increased permeability to Na + and K+ ions, provoking a net depolarization to about 100mV from the resting potential of about -60mV. This generates an action potential which spreads along the surface of the postsynaptic cell membrane which in turn may trigger Ca 2+ movement to the cytosol in the synaptic terminal to generate a new response. Several proteins inside the post synaptic terminal are involved in this process. It is generally accepted that learning and memory result from structural and biochemical changes in specific synapses which alter neurotransmitter release and post synaptic action. These alterations are perceivable electrophysiologically as a long term potentiation (LTP),long term depression (LTD), or a combination of both. 

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Author Biographies

  • Ana C. Polli Lopes, Departamento de Patologia, Faculdade de Medicina de Ribeirão Preto da Universidade de São Paulo - FMRP/USP

    Aluna de pós-graduação no Departamento de Patologia da Faculdade de Medicina de Ribeirão Preto da Universidade de São Paulo - FMRP/USP

  • Luciana Casaletti Rosa, Departamento de Morfologia, Faculdade de Medicina de Ribeirão Preto da Universidade de São Paulo - FMRP/USP
    Aluna de pós-graduação no Departamento de Morfologia da Faculdade de Medicina de Ribeirão Preto da Universidade de São Paulo - FMRP/USP
  • René de O. Beleboni, Departamento de Bioquímica da Faculdade de Medicina de Ribeirão Preto da Universidade de São Paulo -FMRP/USP
    Aluno de pós-graduação no Departamento de Bioquími ca da Faculdade de Medicina de Ribeirão Preto da Universidade de São Paulo - FMRP/USP
  • Rodrigo N. R. Pereira, Departamento de Fisiologia da Faculdade de Medicina de Ribeirão Preto da Universidade de São Paulo - FMRP/USP
    Aluno de pós-graduação no Departamento de Fisiologia da Faculdade de Medicina de Ribeirão Preto da Universidade de São Paulo - FMRP/USP
  • Carlos A. C. de Vasconcelos, Departamento de Patologia da Faculdade de Medicina de Ribeirão Preto da Universidade de São Paulo -FMRP/USP

    Aluno de pós-graduação no Departamento de Patologia da Faculdade de Medicina de Ribeirão Preto da Universidade de São Paulo - FMRP/USP

  • Jorge E. Moreira, Departamento de Morfologia da Faculdade de Medicina de Ribeirão Preto da Universidade de São Paulo -FMRP/USP

     

    Professor do curso de pós-graduação, RMF 5751, “Aspectos Moleculares da Transmissão Sináptica”- Departamento de Morfologia da Faculdade de Medicina de Ribeirão Preto da Universidade de São Paulo -FMRP/USP. 

     

     

Published

1998-06-30

Issue

Section

Review

How to Cite

1.
Lopes ACP, Rosa LC, Beleboni R de O, Pereira RNR, Vasconcelos CAC de, Moreira JE. Molecular aspects of synaptic transmission. Medicina (Ribeirão Preto) [Internet]. 1998 Jun. 30 [cited 2024 Jun. 26];32(2):167-88. Available from: https://revistas.usp.br/rmrp/article/view/12692