Scientists have identified a chemical in the brain popular aquarium fish of the family Cyprinidae Danio rerio (“Ladies stocking”, or, Zebra, chelates-rerio), which contributes to the restoration of the retina. This discovery, according to researchers, can help to cure blindness in humans.
The discovery increases the likelihood that physicians will achieve regeneration of the retina of the human eye with a natural “repair”the damage caused by degenerative diseases and trauma of the retina, including age-related macular degeneration and pigmentary retinitis, scientists say.
“A predominant belief that the process of regeneration in the retina of fish caused by secreted growth factors, but our results show that it causes the neurotransmitter GABA (Gamma-aminobutyric acid),” said James Patton, Professor at Vanderbilt University in the United States.
“All the regeneration model suggests that the retina must be severely damaged to regenerate, but our research has shown that GABA can cause this process even in the intact retina,” explains Patton.
It turns out that the structure of the retina of fishes and mammals are basically the same.
Despite the fact that the retina is very thin – with a thickness of less than 0.5 mm – it contains three layers of nerve cells: photoreceptors that detect light, horizontal cells, which integrate signals from photoreceptors and ganglion cells that receive visual information and send it to the brain.
In addition, the retina contains a special type of adult stem cells – glial müller cells, which provide mechanical support and electrical insulation of all three layers. In the retina of fish, müller cells also play a key role in regeneration.
When triggered the mechanism of regeneration, the glial müller cells dedifferentiate, begin to proliferate (growth of tissue), and then differenciate to replace damaged nerve cells. Müller cells are also present in the retina of mammals, but not restored.
Graduate student Mahesh RAO from the University of Vanderbilt University put forward the idea that GABA is usually a fast-acting neurotransmitter that promotes calm nervous activity by inhibiting neural impulses in the brain – can be the impetus for the regeneration of the retina.
The idea was originally based on the results of the study of the hippocampus (part of the limbic system of the brain) of mice that found that Gamma-aminobutyric acid controls the activity of stem cells.
In the end, the team of scientists, led by Professor Patton conducted a series of experiments with the fish Danio rerio, which found that high concentrations of GABA in the retina cells keep Miller at rest, and that they begin to mutate and proliferate in the fall the decrease in the concentration of GABA.
The researchers tested their hypothesis in two ways: blinding zebrafish and making injections of drugs that stimulate the production of GABA and the introduction of healthy zebrafish of an enzyme that reduces the level of GABA in their eyes.