A fish helps the study of mental disorders

Currently, when you want to investigate about mental disorders In animal experiments, genetically manipulated mice are often used to produce these disorders, which is very invasive and, of course, harmful to these animals.

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

The Case of the Eyeless Cavefish

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 specific case is the fish known as the Mexican tetra (Astyanax mexicanus)..

This rare aquatic species has a special feature: 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, lives in aquatic areas that are found inside certain caves and its eyeballs have gone degrading over time by living in the dark, to save energy, so that their study can reveal more data on which genes participate in the formation of the eyes.

And that's how Masato Yoshizawa (a biologist from 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 just a case of loss of organs, but also become a good model for the study of mental illnesses in humans, As the autism wave 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 both is possible. In this process it is possible to quantify a trait and how it is distributed in its offspring, a technique used by Gregor Mendel, the 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 investigations, Yoshikawa and his collaborators found that the two populations of tetra not only were differentiated by their physical appearance, but there was also a big difference in their behavior social. Those that inhabit surface waters are sociable and even have a social structure among themselves. Instead, cavemen are solitary, what's more, they reject company. In addition, they present symptoms of anxiety and hyperactivity and never sleep.

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

Medicating cave fish

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

But the thing does not end here, since with another essay he treated the solitary fish with the psychopharmaceuticalantidepressant Fluoxetine (also known by its brand name Prozac) in combination with the antipsychotic Clozapine, causing this that the fish became sociable, lowered their anxiety levels, that they swam less frequently and that they could sleep. With this, Yoshikawa's team wanted to show that these fish react in a similar way to a human patient.

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 lack of sleep, hyperactivity either anxietyAnd all this in a natural way.

There is still much to be done and more tests to be carried out, but for now the evidence indicates that the Mexican tetra fish can become in a new tool to follow studies of mental disorders, both at the level of the genetic basis and in the investigation of new drugs. Even so, some experts emphasize that there is a limitation in this model, since it is a fish, since humans and fish are separated by 400 million years of evolution and the results cannot be extrapolated so far light.