A fish helps in the study of mental disorders

Incredible but true. A fish that helps us to understand various psychological disorders.

Currently, when we want to investigate mental disorders in animal experiments, we usually use genetically manipulated mice to produce these disorders, which is very invasive and, of course, harmful to these animals.

However, a recent discovery involving a curious fish opens the door to a curious fish opens the door to the possibility of investigating mental disorders without altering the genes of domestic without altering the genes of domestic species.

The case of the eyeless cave fish

In nature we can find beings that fascinate the most curious and become the object of study by researchers who want to unravel all their secrets. A very concrete case is the fish known as the Mexican tetra (Astyanax mexicanus).. 

This rare aquatic species has a special characteristic: it exists in two different forms, one with eyes and the other without. The first form lives in rivers, while the other, in addition to being albino, inhabits aquatic areas found inside certain caves and its eyeballs have degraded over time as it lives in the dark, to save energy, so its study may reveal more data on which genes are involved in the formation of the eyes.

And so it was that Masato Yoshizawa (a biologist at the University of Hawaii) along with his team, chose this animal for testing. The most surprising thing is that this animal could have more secrets, not only be a case about organ loss, but also become a good model for the study of mental illnesses in humans, such as autism or schizophrenia. Let's see how it happened.

The comparative study to understand mental disorders

Thanks to the existence of these two populations within the same species, it has been possible to study their genetic code, making crosses between the two at the laboratory level, since reproduction between the two is possible.The existence of these two populations within the same species has made it possible to study their genetic code, making crosses between the two at the laboratory level, since reproduction between the two is possible. In this process it is possible to quantify a characteristic and how it is distributed in their offspring, a technique used by Gregor Mendel, father of genetics, in his study of peas. To give an example, thanks to this it has been known that a mutation in a gene known as "cbsa" is responsible for a population not developing eyes.

During their research, Yoshikawa and his collaborators found that the two tetra populations not only differed in their physical appearance, but also differed greatly in their social behavior. Those that live in surface waters are sociable and even have a social structure among themselves. Cavers, on the other hand, are solitary, indeed, they reject company. In addition, they show symptoms of anxiety and hyperactivity and never sleep.

With these data in mind, in a first experiment, Yoshikawa again crossed the populations to see to what extent this difference in social behavior is genetically rooted or based on learned behaviors in a specific context.

Medicating cave fish

The results of his trials were presented at the 23rd International Conference on Underground Biology in Fayeteville, Arkansas. Yoshikawa states that 90% of the 101 classical genes that are related to the risk of developing mental illness in humans are present in the genome of the human genome. in humans are present in the Mexican tetra genome. Data that could turn this animal into a new model for the study of these diseases.

But it doesn't end there, as with another trial he treated the solitary fish with the Antidepressant psychopharmaceutical Fluoxetine (also known by its brand name Prozac) in combination with the antipsychotic Clozapine, causing the fish to become sociable, lower their anxiety levels, swim less frequently and sleep. With this, Yoshikawa's team wanted to demonstrate that these fish react in a similar way as a human patient would.

Conclusions

The importance he wants to give with this finding is to have an animal specimen that has "symptoms" that are present in autism or schizophrenia, such as the absence of sleep, hyperactivity or anxiety, and all this in a natural way.

There is still much to be done and more tests to be performed, but for the moment the evidence indicates that the Mexican tetra fish can become a new tool for further studies of psychic disorders, both at the genetic level and in the research of new drugs. Even so, some experts stress that there is a limitation in this model, as it is a fish, since humans and fish are separated by 400 million years of evolution and the results cannot be extrapolated so lightly.