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An association between mitochondria and microtubules in synaptosomes and axon terminals of cerebral cortex
Abstract:
A substantial number of synaptosomes prepared from rat cerebral cortex were found by electron microscopy to contain a horseshoe-shaped mitochondrion flanked by an arc of three to ten microtubules opposite the synaptic membrane specializations. The microtubules were replaced by characteristic paracrystals following the incubation of synaptosomes with vinblastine sulfate. A similar spatial organization of microtubules and mitochondria was also observed in some axon terminals of the cerebral cortex in situ. The significance of this novel observation is discussed with regard to the role of microtubules in axonal transport at the synaptic terminal and previous reports on the identification of tubulin in synaptosomes and subsynaptic structures.
Insights
Researchers discovered a unique arrangement of microtubules and mitochondria within rat brain synaptosomes. This structure, observed via electron microscopy, may play a role in synaptic function and axonal transport.
Area of Science:
- Neuroscience
- Cell Biology
- Electron Microscopy
Background:
- Synaptosomes are crucial for studying synaptic transmission.
- Microtubules are known components of neuronal structure and transport.
- The precise organization of organelles within synaptosomes is not fully understood.
Purpose of the Study:
- To investigate the ultrastructural organization of organelles within rat cerebral cortex synaptosomes.
- To explore the relationship between microtubules, mitochondria, and synaptic membrane specializations.
- To examine the effect of vinblastine sulfate on synaptosome structure.
Main Methods:
- Preparation of synaptosomes from rat cerebral cortex.
- Analysis of synaptosome ultrastructure using electron microscopy.
- Incubation of synaptosomes with vinblastine sulfate.
Main Results:
- A consistent horseshoe-shaped mitochondrion was observed, flanked by 3-10 microtubules, positioned opposite synaptic membrane specializations.
- Incubation with vinblastine sulfate induced the formation of paracrystals, replacing the microtubules.
- Similar microtubule-mitochondria spatial arrangements were found in some in situ cerebral cortex axon terminals.
Conclusions:
- The observed spatial organization suggests a potential role for microtubules in synaptic terminal function.
- Findings support the presence and significance of tubulin in synaptosomes and subsynaptic structures.
- This arrangement may be critical for axonal transport and synaptic vesicle dynamics.