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Changes in synaptic ultrastructure during reactive synaptogenesis in the rat dentate gyrus
Diano F Marrone1, Janelle C LeBoutillier, Ted L Petit
1Department of Psychology, University of Toronto, 1265 Military Trail, Toronto, ON, Canada M1C 1A4.
Brain Research
|March 27, 2004
Summary
Reactive synaptogenesis (RS) involves changes in synapse shape, particularly curvature, which is crucial for brain recovery after injury. This study quantifies these morphological changes in the dentate gyrus following lesions.
Area of Science:
- Neuroscience
- Cell Biology
- Structural Plasticity
Background:
- Reactive synaptogenesis (RS) is critical for recovery from brain injury and disease.
- Mathematical models suggest synaptic morphology influences synaptic transmission.
- Quantitative morphometry is needed to understand RS-induced changes.
Purpose of the Study:
- To quantitatively assess synaptic morphology during RS in the dentate gyrus.
- To investigate the role of synaptic curvature and size in response to injury.
- To explore how proximity to damage affects synaptic changes.
Main Methods:
- Serial electron microscopy was used to analyze dentate gyrus synapses.
- Synaptic morphology was assessed at multiple time points (3, 6, 10, 15, 30 days) post-lesion.
- Unilateral entorhinal cortex lesions were induced to study RS.
Main Results:
- Synaptic curvature is a plastic feature, with concave synapses showing increased curvature during RS.
- Flat synapses exhibited unique growth patterns relevant to development and activation.
- Synaptic size and curvature changes varied with proximity to the lesion site.
- In the medial molecular layer (MML), curvature increased proportionally with size; in the intermediate molecular layer (IML), curvature increased disproportionately.
Conclusions:
- Synaptic curvature is a dynamic and important feature of reactive synaptogenesis.
- The observed morphological changes suggest distinct roles for different synapse types and locations in brain repair.
- Understanding these quantitative changes offers insights into neural plasticity and recovery mechanisms.