Biologists have discovered the phenomenon of despair in fish

11:00, June 2, 2020

This has greatly simplified the search for antidepressants.

Scientists for the first time in the world validated a novel behavioral paradigm, the zebrafish tail immobilization (ZTI) test, as a potential method to assess zebrafish despair-like behavior. An article with the results of the research is published in the Journal of Neuroscience Methods. The project was funded by a grant of Russian Foundation for Basic Research “Search, description and detailed study of the depression-related phenotype in Danio rerio”.

A group of researchers from Ural Federal University, St. Petersburg State University and Almazov National Medical Research Center (St. Petersburg), together with colleagues from Moscow, Novosibirsk, Brazil and China, found out that phenazepam did not lead to changes in fish behavior, electric shock and alarm pheromone decreased their activity, and antidepressants - both amitriptyline and sertraline - increased it, that indicates a decrease in anxiety. In addition, exposure to antidepressants before testing increased the intensity of serotonin and dopamine use in the brain of zebrafish, which are closely associated with depression and human emotions.

For the first time, we discovered the phenomenon of despair in zebrafish. Then we found that the use of antidepressants for zebrafish leads to approximately the same changes as for rodents and people exposed to antidepressants. Thus, we “pushed back” the model of depression based on learned helplessness by 340 million years, as the first jaw fish arose during the evolution 400 million years ago, and rodents - 60 million years ago, ”explain the developers of the model, the head of the research group, Leading Researcher, Research Laboratory for Advanced Studies in Petrochemistry, Chemical Technology and Biotechnology, UrFU Alan Kaluev and Senior Researcher, Laboratory of Biological Psychiatry, Institute of Translational Biomedicine, St. Petersburg State University Konstantin Demin.

The experimental results have very important applications. According to Alan Kaluev, since depression is of very ancient origin, the targets for the treatment must be sought in conservative molecular mechanisms common for fish, rodents and humans. 

“Given that on a genetic basis fish and humans share a 70% sequence similarity, we have made the search for potential biological targets for antidepressants much less complex and less expensive than when working with laboratory rodents. Using zebrafish and affecting them with various substances, scientists will quickly find, test and select new, more advanced drugs against depression - the most widespread, debilitating and disabling brain disease affecting almost 10% of people, many of whom commit suicide because of inefficient treatment, ” summarizes Professor Kaluev.