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There’s new evidence that suggests a common probiotic found in supplements and yogurt could lower anxiety.

In a series of studies published in the journal Scientific Reports, researchers tested how stressed-out zebrafish behaved after doses of Lactobacillus plantarum.

“Our 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,” says Aaron Ericsson, a research assistant professor in veterinary pathobiology at the University of Missouri.

Ericsson says zebrafish are often used to screen drugs but are emerging as a model for neurobehavior.

Anxious fish

To test the effect, scientists added the bacteria to certain tanks housing zebrafish; other tanks of zebrafish received no probiotics. Then, the researchers introduced environmental stressors to both groups, such as draining small amounts of water from the tank and overcrowding.

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

By analyzing the gene pathways of both groups of fish, the research team found zebrafish that received the supplements showed a reduction in the metabolic pathways associated with stress.

“By measuring the genes associated with stress and anxiety, our tests were able to predict how this common probiotic is able to benefit behavioral responses in these fish,” says Daniel Davis, assistant director of the MU Animal Modeling Core. “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.”

To test their theory further, the researchers measured the movements of fish in their tanks using sophisticated computer measuring and imaging tools. Previous studies of fish behavior have found that fish that are stressed tend to spend more time at the bottom of their tanks.

Once the fish were administered probiotics, they tended to spend more time toward the top of the tanks—a change in behavior that suggests they were less stressed or less anxious.

“Using zebrafish, we’ve developed a relatively inexpensive platform for testing of other species of bacteria and probiotics and their potential benefit on different systems of the body,” Ericsson says.

Source: University of Missouri