$~~~~$Zebrafish, named for their characteristic stripes, have been a popular test subject for researchers. Only a few centimeters in length, the fish breed easily in captivity, grow quickly, and their transparent body makes it easy to study their organs. Above all, they possess some amazing “self-healing” power. When part of their heart is removed, they can grow it back in a matter of weeks. When blinded, they can quickly regain the ability to see.
$~~~~$Recent studies show that humans and zebrafish have the same major organs and share 70 percent of the genes. Moreover, 84 percent of human genes associated with disease find a counterpart in zebrafish. Scientists thus hope that understanding the self-healing mystery of the fish may one day allow humans to regenerate such organs as eyes, hearts, and spines.
$~~~~$Researchers at Vanderbilt University are particularly interested in zebrafish retina regeneration. They have learned that damage of retina can cause blindness in zebrafish, yet it only takes about three to four weeks before vision is restored. The structure and cell types of zebrafish retinas are almost identical to those of humans. If the process can be replicated in humans, it may give rise to new treatments for blindness caused by retinal damage.
$~~~~$In order to know exactly how zebrafish retina is regenerated, the team looked at the neurotransmitter gamma-aminobutyric acid (GABA), a chemical messenger in the brain that reduces the activity of neurons. They found that lowering GABA levels in zebrafish can trigger retina regeneration, while a high level of GABA concentration will suppress the regeneration process. This suggested that GABA plays an important role in the fish’s ability to regain their sight.
$~~~~$The team is beginning to test the GABA theory on mice. If that works, human trials will be next on the agenda. If the research proves successful in humans, some of the nearly 40 million blind people worldwide may one day have a tiny, striped fish to thank.****