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A review on electron microscopy and neurotransmitter systems
Fernando Torrealba1, Maria Angélica Carrasco
1Departamento de Ciencias Fisiológicas, Fac. Ciencias Biológicas, Pontificia Universidad Católica de Chile, Alameda 340, Santiago, Chile. ftorreal@genes.bio.puc.cl
Brain Research. Brain Research Reviews
|December 2, 2004
Summary
Transmission electron microscopy reveals diverse neurotransmitter storage, challenging the classical synapse model. Some neurons, like those in the cortex, may not use neuropeptides due to lacking specific vesicles.
Area of Science:
- Neuroscience
- Cell Biology
- Microscopy
Background:
- Classical understanding of chemical synapses is evolving.
- Neuronal connections exhibit greater microstructural diversity than previously thought.
Purpose of the Study:
- To review transmission electron microscopy (TEM) contributions to understanding brain circuits and neurotransmitter systems.
- To highlight the distinct roles of vesicle types in neurotransmission.
Main Methods:
- Review of transmission electron microscopy studies.
- Analysis of synaptic vesicle morphology and transmitter content.
Main Results:
- Fast transmitters (glutamate, GABA) are in small, clear synaptic vesicles (SSV) released at synapses.
- Neuropeptides are exclusively in large dense-core vesicles (LDCV) released extrasynaptically.
- Amine transmitters can be in LDCV and released synaptically or extrasynaptically.
Conclusions:
- Pyramidal cortical and dorsal thalamic neurons may lack LDCV, suggesting they do not use neuropeptides.
- This aligns with the fast information processing characteristic of cortical and thalamic functions.