Damage to our eyes through injury and degenerative diseases irreversibly affects our vision, yet the eyes of fish can fully recover. Like ours, their retina is composed of four cell types: light-sensitive photoreceptors, horizontal cells (pictured in red, in a zebrafish retina) that integrate their signals, ganglion cells transmitting them to other regions of the brain, and supportive Müller glia (in green). In fish, these glia have a remarkable capacity. Damage induces them to revert to stem cells, multiply and differentiate, producing the necessary cells to rebuild a functioning retina. Recent research suggests that this regeneration may be triggered by low levels of a neurotransmitter named GABA. Inhibiting GABA signalling stimulates changes in the Müller glia, while raising GABA levels has the opposite effect, hampering the recovery of blinded zebrafish. Manipulating neurotransmitter levels could have similar consequences for the human retina, raising new possibilities for restoring vision.
Written by Emmanuelle Briolat
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