Probiotics Reduce Stress Levels in Fish Model


New research results out of the University of Missouri suggest zebrafish taking probiotics experienced lower levels of stress-related behaviors and neurological changes.

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New research results out of the University of Missouri (MU) suggest zebrafish that were fed Lactobacillus planatarum probiotics experienced lower levels of stress-related behaviors and neurological changes. The series of studies found that fish taking the probiotics showed a metabolic response suggesting reduced stress activity, in addition to responding to environmental stress with behaviors indicating less anxiety than fish in a control group.

L. planatarum was chosen because it commonly appears in yogurt and probiotic supplements, while zebrafish were studied because they “are an emerging model species for neurobehavioral studies, and their use is well-established in drug screening,” according to Aaron Ericsson, director of the MY Metagenomics Center and author of the study, in the study announcement.

In the first study, researchers added the probiotics to some tanks containing zebrafish, while other tanks with zebrafish received no probiotics. The fish were then subjected to environmental stressors, such as overcrowding and draining small amounts of water from their tanks.

“Each day we introduced a different stressor-tests that are validated by other researchers and cause high anxiety among zebrafish,” said Elizabeth Bryda, professor of veterinary pathobiology in the MU College of Veterinary Medicine. “These are common environmental stress patterns, such as isolation stress and temperature change, so it made the tests relevant to humans as well.”

The scientists then analyzed the gene pathways of the fish and found that the probiotic group of zebrafish experienced a reduction in several metabolic pathways associated with stress. Daniel Davis, assistant director of the MU Animal Modeling Core, explained that measuring the genes associated with anxiety allowed researchers to “predict how this common probiotic is able to benefit behavioral responses in these fish.”

“Essentially, bacteria in the gut altered the gene expression associated with stress- and anxiety-related pathways in the fish, allowing for increased signaling of particular neurotransmitters," Davis said.

Additionally, researchers measured how the zebrafish moved in their tanks with sophisticated measuring and imaging tools. The group of fish that were fed probiotics tended to spend more time near the top of their tanks, a behavioral sign indicating they were less stressed, according to the researchers. Previous studies have found stressed fish tend to spend more time near the bottom of their tanks.

Based on the results, Ericsson explained that the study “has shown that simple probiotics that we normally use to keep our digestive tract in sync could be beneficial to reducing our stress levels as well.” He added that MU’s work with zebrafish also offers a “relatively inexpensive platform for testing of other bacteria and probiotics and their potential benefit on different systems of the body.”


Read more:

2016 Probiotic Research Update

Dietary Supplements for Stress-Related Burnout

Probiotics May Reduce Inflammation, Performance Degradation Following Exercise: SupplySide West Report


Michael Crane
Associate Editor
Nutritional Outlook Magazine


Davis DJ et al., “Lactobacillus plantarum attenuates anxiety-related behavior and protects against stress-induced dysbiosis in adult zebrafish,” Scientific Reports, vol. 6 (September 2016): 33726

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