Characterization of optic nerve regeneration using transgenic zebrafish

Area of Science:

• Neuroscience
• Regenerative Medicine
• Zebrafish Model Systems

Background:

• Mammalian central nervous system (CNS) regeneration is limited, unlike in fish.
• Zebrafish are a valuable model but lack tools for adult CNS axon regeneration studies.
• Visualizing regenerating axons in the adult zebrafish CNS is crucial for understanding repair.

Purpose of the Study:

• To develop and validate a novel tool for visualizing axon regeneration in the adult zebrafish CNS.
• To enable detailed anatomical and molecular analysis of CNS axon repair in vivo.
• To facilitate screening of compounds and genetic manipulations for enhancing regeneration.

Main Methods:

• Utilized transgenic zebrafish expressing enhanced green fluorescent protein (GFP) under a GAP-43 promoter.
• Employed wholemount tissue clearing and confocal microscopy for visualizing axons in the optic nerve.
• Established dissociated retinal cultures for in vitro neurite growth assays.

Main Results:

• GFP expression was restricted to young retinal ganglion cells (RGCs) and their axons in naive retinae.
• Optic nerve crush induced significant GFP expression in RGCs and axons post-injury.
• Regenerating axons were visualized beyond the injury site by 2 days and past the optic chiasm by 4 days post-injury.
• Detailed visualization of the entire optic nerve regeneration process from 6 to 14 days post-injury was achieved.

Conclusions:

• The developed GFP-based system provides a powerful tool for studying CNS axon regeneration in adult zebrafish.
• This methodology allows for in vivo analysis of regeneration and in vitro screening of therapeutic interventions.
• The findings open new avenues for investigating molecular mechanisms of successful CNS regeneration.