Evaluating the effects of pro-myelinating drugs on motor function and myelination in a zebrafish model of genetic leukoencephalopathy

Genetic leukoencephalopathy (gLE) is a white matter disorder affecting the central nervous system, causing hypomyelination, developmental delays, motor deterioration, and cognitive, visual, and hearing impairments. Its clinical variability makes diagnosis challenging. A novel homozygous missense mutation, p.Cys846Gly in VACUOLAR PROTEIN SORTING 11 (VPS11), has been linked to infantile-onset gLE in humans. A zebrafish vps11 mutant model was developed to replicate gLE-like hypomyelination and sensorimotor deficits. This study investigates the effects of Clemastine, a pro-myelinating drug, on motor function and myelination in zebrafish larvae with mutations in the vps11 gene. We exposed zebrafish larvae to this drug during a critical period of early nervous system development, from 2 to 4 days post-fertilization (dpf), and assessed visuomotor responses at 7 dpf. Although Clemastine significantly increased the number of oligodendrocytes, it failed to improve visuomotor function in vps11 mutants. These findings imply that increasing oligodendrocyte numbers does not necessarily result in improved behavioral responses in vps11 mutants.