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Axonal cytoskeletal changes after non-disruptive axonal injury
S S Jafari1, W L Maxwell, M Neilson
1Laboratory of Human Anatomy, University of Glasgow, UK.
Journal of Neurocytology
|April 1, 1997
Summary
Diffuse axonal injury causes rapid cytoskeletal changes in axons. Neurofilament compaction and microtubule loss occur within hours, disrupting axonal structure and leading to secondary axotomy.
Area of Science:
- Neuroscience
- Cell Biology
- Pathology
Background:
- Diffuse axonal injury (DAI) is a primary consequence of traumatic brain injury.
- Axonal swelling and secondary axotomy are key pathological events in DAI.
- Cytoskeletal alterations underlying these events remain poorly understood.
Purpose of the Study:
- To quantitatively analyze cytoskeletal changes in axons following DAI.
- To investigate the temporal dynamics of these changes in a relevant animal model.
Main Methods:
- Adult guinea-pig optic nerves subjected to stretch-injury.
- Quantitative analysis of axonal cytoskeletal components (neurofilaments, microtubules) at 4 hours post-injury.
- Microscopic examination of longitudinal and cross-sections.
Main Results:
- Significant increase in small axons (<0.5 micron) with compacted neurofilaments.
- Larger axons (>2.0 microns) showed altered spacing of cytoskeletal elements.
- Two distinct responses in larger axons in the damaged nerve segment: neurofilament compaction/microtubule loss or increased spacing/loss of neurofilaments and microtubules.
- Neurofilament compaction correlated with axolemma disruption.
Conclusions:
- DAI induces rapid, distinct cytoskeletal changes within hours.
- These changes, including neurofilament compaction and microtubule loss, precede secondary axotomy.
- The observed time course is faster than that of Wallerian degeneration.