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Alignment and intracytoplasmic disintegration of synaptic vesicles in the brain cortex
F González-Aguilar1, R H Alzola
1Cátedra de Histología, Facultad de Ciencias Veterinarias, U.N.C.P.B.A., Tandil, Argentina.
Neuroscience
|January 1, 1989
Summary
Synaptic vesicles disintegrate within the presynaptic terminal, not released via exocytosis. This finding holds true across various conditions, challenging traditional neurotransmission models.
Area of Science:
- Neuroscience
- Cell Biology
- Biochemistry
Background:
- The prevailing model of neurotransmission involves synaptic vesicles releasing neurotransmitters into the synaptic cleft via exocytosis.
- This study investigates an alternative mechanism for synaptic vesicle behavior.
Purpose of the Study:
- To investigate the fate of synaptic vesicles upon interaction with the presynaptic membrane.
- To explore the influence of fixative concentration, physiological activity, and cell depolarization on synaptic vesicle behavior.
Main Methods:
- Perfusion fixation using highly concentrated aldehydes.
- Microscopic analysis of synaptic structures under various experimental conditions (ischemia, pharmacological agents).
Main Results:
- Synaptic vesicles were observed to disintegrate within the presynaptic terminal upon contact with the presynaptic membrane.
- This disintegration occurred irrespective of aldehyde concentration, even at low levels.
- Under conditions of acute ischemia and depolarization, vesicles aligned in rows towards the synaptic cleft.
- Post-mortem studies confirmed a specific flow of vesicles toward the synaptic cleft.
Conclusions:
- The findings challenge the classical exocytosis model for synaptic vesicle release.
- Synaptic vesicles may undergo disintegration at the presynaptic membrane rather than fusing with it.
- Further research is needed to elucidate the precise mechanisms and implications of this observed phenomenon.