If you went to high school and took a biology class, then you must be aware of the fruit fly, formally known by its scientific name, Drosophila melanogaster. The fruit fly has been used in science classes and genetic laboratories for decades. In fact, “fruit flies share 75% of the genes that cause disease with humans, so scientists can learn about human genetics by studying fruit fly genetics,” according to a UNC research lab. Today, fruit flies are still used for a multitude of genetic studies, and a recent area of interest has been mental health, in particular, anxiety.
Size of sample matters
In order to produce a good study there are a few things that are necessary, one being a large sample size. Fruit flies are small and it is very easy to study hundreds or even thousands of them, making for a large sample size in any study. In addition, fruit flies are inexpensive. “Using flies lends the advantages of a smaller animal brain, more sophisticated genetic tools, and greatly larger sample sizes. Evolutionary conservation of function between animal species means findings in fly could eventually be translated into rodent anxiety research,” according to one report about a study that was recently published in Current Biology.
Anxiety disorders are prevalent in the United States. An estimated 18 percent of Americans have anxiety, according to the literature, and without a cure, this number will only rise due to major stress in the American culture. Fruit flies are now being used to study anxiety and the genetics potentially involved in this disorder. Initially, rodents were used as subjects in the study, but it was difficult to obtain such a large sample size. A recently published study used fruit flies because it appeared that fruit flies exhibited the same behaviors as rodents: wall climbing or wall following. Wall following behavior in rodents has strongly been linked to anxiety when these rodents are placed in close chambers. So the scientist tied the two behaviors between flies and rodents together.
The serotonin paradox
In this fruit fly study, researchers introduced two extreme ends of the spectrum to test whether flies exhibited different levels of behavior based on their anxiety levels. Flies were given Valium, a well-known benzodiazepine used to treat anxiety. The flies showed less wall following after the Valium was administered compared to the control flies. Additionally, external stress in terms of heat was applied to the closed environments in which the flies were contained. When heat was introduced to the closed containers, the flies demonstrated more of a wall following behavior.
This experiment proved that anxiety is an emotion with a strong evolutionary related component. Future studies are needed to demonstrate the specific genes involved as well as a potential treatment modality to trigger these genes. “One of the outstanding puzzles in psychiatric research is that even though it’s clear that serotonin plays a role in anxiety, widely prescribed serotonin-related drugs like Prozac show little efficacy on emotional disorders. They hope to gain new insight into this ‘serotonin paradox’ by studying the role of this neurotransmitter in fly anxiety,” the article concluded regarding the Current Biology study.
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About the author
Kristen Fuller, M.D., is a senior staff writer at the Sovereign Health Group and enjoys writing about evidence-based topics in the cutting-edge world of medicine. She is a physician and author, who also teaches, practices medicine in the urgent care setting and contributes to medicine board education. She is also an outdoor and dog enthusiast. For more information and other inquiries about this article, contact the author at firstname.lastname@example.org.