The effects of electrical stimulation on neurite outgrowth of goldfish retinal explants

The central nervous system (CNS) in adult mammals loses the ability to regenerate after injury. Although electrical stimulation (ES) has been shown to promote neural regeneration, the underlying mechanisms by which ES enhances CNS regeneration remain elusive. The aim of the present study was to investigate the effect of ES on neurite outgrowth of goldfish retinal explants. The optic nerve of adult goldfish was intraorbitally crushed 7-14 days before retinal explants preparation. The explants were cultured in a laminin-coated indium tin oxide (ITO, transparent conducting oxide) device for ES application. Various strengths and waveforms of ES were applied to examine their effect on neural outgrowth. When the retinal explants were stimulated for 1h with intermittent pulses on day 1 (20 Hz; 10 pulses every 2s), the regenerated neurite length was significantly increased compared to explants that were stimulated with continuous square waves or continuous pulses over the same time course. It was also found that increased ES strength and repeated ES each day can enhance neurite outgrowth significantly. These results suggest that intermittent pulse ES is able to promote neurite regeneration most effectively in goldfish retinal explants, and that this electrically stimulated neurite outgrowth using ITO conductive electrodes may provide a useful platform for investigating cellular mechanisms of CNS regeneration.