It turns out humans aren't the only ones to have the blues. Fish can become "depressed-like" when experiencing chronic stress, according to a new study. This makes them a good model for understanding and treating psychiatric problems in humans.
"In the future, we could use the fish to search for other therapies," study co-author Dr. Herwig Baier, director of the Max Planck Institute of Neurobiology, told The Huffington Post. "This experiment may find drugs that act as well as Prozac, or better, with less side effects."
But don't get your hopes up too fast. "Even if we find a drug that works in fish we're still a long way from knowing if it will work in human patients," Dr. Baier said.
For the study, the researchers took two kinds of zebrafish -- one normal, and one with a mutant gene -- and isolated them in an unfamiliar environment. While the normal fish was able to adjust after a few minutes, the mutant fish sat still at the bottom of the tank and took much longer to return to normal, which is shown in the video above.
"The [mutant] fish have mutation in a receptor that binds cortisol -- they cannot dial down their brain's stress response," Dr. Baier said.
In stressful situations, animals tend to release stress hormones -- including cortisol -- to mobilize the body and ready them for a "fight or flight" reaction. Eventually, the body will return to baseline as cortisol binds to receptors and stops cells from releasing more stress hormones.
The mutant fish in the study could not regulate the release of its stress hormones, which resulted in abnormally high hormone levels, and signs of depressed behavior, the researchers noted.
The fish then sprung back to life when the researchers pumped its water with the antidepressant Prozac.
"Although there are a whole range of drugs available for depression, no one yet knows what the relationship is between their effect and the stress hormones," Dr. Baier said in a written statement. "Our findings provide the first evidence of a possible connection."
The study was published in the June 2013 issue of Molecular Psychiatry.
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