We often think of depression as solely affecting humans, and we rarely associate animal behavior to this disorder. However, researchers have recently discovered that disrupting stress responses in zebrafish can trigger depression-like behavior. These findings help to corroborate the long-believed notion that one’s emotional wellbeing depends on an individual’s ability to respond to stress.
Zebrafish are a popular model system used in biological research because their embryos are transparent, easy to manipulate, and they are more closely related to humans than other invertebrate models such as C.Elegans and Drosophila. This study represents the first case in which a zebrafish mutant has been observed to develop a psychological disorder. Baier and his colleagues noticed that zebrafish with genetic mutations in their glucocorticoid (GC) receptor genes, when repeatedly isolated from others, stopped swimming and hid in the corners of the tank. Isolation from the group acts as a stress inducer in this experiment, and increases the level of stress hormones in the zebrafish. In normal zebrafish, this increased level of stress hormone would be balanced by GC receptor genes, however, zebrafish with GC receptor mutations could not control their levels of stress hormone and thus showed signs of depression. When the mutated fish were placed in tanks containing fluoxetine (Prozac), their abnormal behavior was reversed.
It is not known yet if similar symptoms of depression in humans can be attributed to genetic mutations in the glucocorticoid receptor genes, but if it does, then new antidepressant treatments should be aimed at resurrecting glucocorticoid function.
- Amanda Grafstein
I never thought about fish having depression, but I have noticed that they can have a lot more personality than most people think, so perhaps it isn't so surprising. Has research into the glucocorticoid receptor genes in humans been started, and if so how far has it gotten?
ReplyDeleteDana Mirsky
Zebrafish can definitely provide us with clues as to how systems in humans are regulated. Did the researchers mention any relationship between serotonin and stress? Prozac increases activation of serotonin receptors, so it would be interesting to see why there could possibly be a decrease in serotonin as a result of stressful experiences.
ReplyDeletePosted by Katie Kalutkiewicz
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ReplyDeleteYeah, I would like to see more data about serotonin levels as a result of stress. That would be interesting. I assume that if prozac increases serotonin receptor activation then there should be a correlation between stress and serotonin. I haven't read any research on that specifically, though.
ReplyDelete- Amanda Grafstein
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ReplyDeleteThat's really interesting, I never considered the psychological effects that isolation can have on fish. I wonder if this has any effect on research performed on fish in isolation. Could isolation maybe be a confounding variable that has gone unnoticed?
ReplyDeleteMuriel Herd
Hi Amanda! So interesting. Very well written.
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