Zebrafish prove invaluable to University of Edinburgh study

For humans, the serotonin-A hormone is generally associated with happiness, but researchers at the University of Edinburgh have discovered that zebrafish use the hormone to repair injuries to their spinal cords.

We have known for a while that some tropical fish are able to rebuild parts of their nervous system. Now, research conducted at the Centre for Neuroregeneration has taken us a step closer to understanding how, and it turns out that the chemical serotonin is vital. Serotonin is a hormone that is present in all humans, although in our systems its role is to shape our moods. You can think of it in terms of how two different languages might use the same word, but give them different meanings.

The Centre’s experiments with serotonin have shown that it is this hormone which is vital to zebrafish for growing new neurons. Scientists hope this will take us a step closer to combatting conditions such as Motor Neuron Disease, a symptom of which is the progressive loss of nerve cells.

Motor neuron disease is not particularly common, affecting around seven in every 100,000 people, however, for its sufferers, the consequences can be devastating; loss of mobility, speech and cognitive function. An insidious condition, initial symptoms can be as innocuous as clumsiness and slurred speech, and often these symptoms start long before people visit their GP. Unfortunately, the condition can only be managed and not cured, regardless of when it is diagnosed.

The study showed how serotonin repaired lesions on the fish’s spinal cord progressively from the face end of the fish. The hormone was shown to make cells multiply when applied to damaged areas, but it did not have an effect on healthy nervous systems.

This is a crucial result: cells which multiply too much present a cancer risk and thus a barrier to a lot of stem cell treatments. On the other hand, it tells us that there is something more allusive occurring. Some mechanism is operating that informs the cells of whether or not they are damaged, working in conjunction with the serotonin to make sure that they only multiply when needed.

Before any clinical advantages can come from the team’s discoveries, we will have to uncover what this is and how it works.

Edinburgh’s Dr Thomas Becker was part of the team who carried out the research. He neatly summed up his hopes for the future when he said: “Understanding how zebrafish are able to repair damaged nerves could one day help us to trigger similar mechanisms in human stem cells. Our hope is that this may eventually lead to new treatments for conditions such as motor neuron disease, for which there is no cure.”

With any luck, this discovery could lead to a cure for this grueling human condition thanks to the help of some Edinburgh scientists, and the humble and tropical zebra fish.

Image: Lynn Ketchum

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