The Optic Nerve Crush Injury Paradigm in African Turquoise Killifish to Study Axonal Regeneration in an Aged Environment

Abstract

In our graying world population, we are increasingly facing brain injuries and age-associated neurodegenerative diseases, which are often characterized by axonal pathology. Here, we propose the killifish visual/retinotectal system as a model for investigating central nervous system repair, more specifically axonal regeneration, in an aging context. We first describe an optic nerve crush (ONC) injury paradigm in killifish to induce and study both de- and regeneration of retinal ganglion cells (RGCs) and their axons. Subsequently, we summarize several methods for mapping different steps of the regenerative process—namely, axonal regrowth and synapse reformation—using retro- and anterograde tracing methods, (immuno)histochemistry, and morphometrical analyses.

Visually Driven Behavior Assays to Study Functionality and Recovery after Damage of the Aged African Turquoise Killifish Visual System

“…For the optokinetic response (OKR) test, fish should be uninjured or bilaterally subjected to optic nerve crush (ONC) as described in Protocol: The optic nerve crush injury paradigm in killifish to study axonal regeneration in an aged environment<prot107828> (Vanhunsel, 2022b). A bilateral ONC is needed for the OKR, as visual input in the uninjured eye can affect the optokinetic response of the injured eye, leading to false positive results.…”

“…For the dorsal light reflex (DLR) test, fish should be uninjured or unilaterally subjected to ONC as described in Protocol: The optic nerve crush injury paradigm in killifish to study axonal regeneration in an aged environment<prot107828> (Vanhunsel et al, 2022b).…”

“…Infusion bag (5-L), filled with aquarium system H2O The optic nerve crush injury paradigm in killifish to study axonal regeneration in an aged environment<prot107828> (Vanhunsel et al, 2022b)). Here, a procedure, split into a habituation phase and the experimental phase, is provided to evaluate this maximal spatial frequency using the OptoMotry system.…”

“…Fish subjected to a unilateral ONC have been shown to swim at an angle (Diekmann, 2015;Vanhunsel et al, 2022a), which gradually goes back to baseline as the nervous system regenerates and the fish regains vision. ONC is described in Protocol: The optic nerve crush injury paradigm in killifish to study axonal regeneration in an aged environment<prot107828> (Vanhunsel et al, 2022b).…”