Immunohistochemical characterization of axonal sprouting in mice

Area of Science:

• Neuroscience
• Alzheimer's Disease Research

Background:

• Transgenic mice are crucial for studying Alzheimer's disease (AD) risk factors and neural plasticity.
• Entorhinal cortex lesions (ECLs) in rats model AD-related denervation and sprouting.
• Hippocampal anatomical differences between mice and rats necessitate wild-type characterization before applying ECL models to mice.

Purpose of the Study:

• Characterize axonal sprouting in wild-type mice following entorhinal cortex lesions.
• Establish a baseline for future studies using ECL models in transgenic mice for AD research.

Main Methods:

• Adult male C57BL/6 mice underwent unilateral perforant pathway transections.
• Hippocampal tissues were stained for acetylcholinesterase (AChE) and synaptic proteins (drebrin, SNAP-25, GAP-43, synapsin, synaptophysin) at multiple time points.
• Ipsilateral-to-contralateral staining densities in the dentate molecular layer were quantified to assess synaptic reorganization.

Main Results:

• Significant depression of ipsilateral terminal marker densities was observed at 28 days postlesion.
• Altered AChE staining and increased SNAP-25 and synapsin immunoreactivity were noted in the inner molecular layer (IML) at earlier time points.

Conclusions:

• C57BL/6 mice demonstrate synaptic reorganization after perforant path transections.
• The IML is identified as a critical region for evaluating and intervening in ECL mouse models of Alzheimer's disease.