What do Zebrafish, Probiotics and Stress Have in Common? New Research!
May 29, 2017
It might surprise you to know that the zebrafish is becoming the go-to model species for neurobehavioral studies. This is why researchers at the University of Missouri turned to this tropical freshwater member of the minnow family to determine if probiotics offered any help to people dealing with anxiety. Probiotics are proven effective in many avenues of health, especially when it comes to digestion. More and more, medical science is making connections between gut microbiota and the central nervous system, as well, which is where the little zebrafish comes into play.
Why Zebrafish?
In biological studies, zebrafish provide some real benefits. For one thing, it is easy to observe and test these fish. Modern science has fully sequenced its genome, as well, which makes genetic testing more practical. The biggest benefit offered, however, is the demonstrably similar neurobehavioral model. The zebrafish is often used in cardiovascular research, immune system studies and to make transgenic models of cancer.
Probiotics and Stress
Since the zebrafish has a proven history in medical research, it seemed clear to a group of scientists at the University of Missouri that it was the right model for their study on human stress levels. Specifically, these researchers wanted to know if the probiotics that work so well to help balance the human digestive tract would also work to lower stress levels.
Stress is a problem that most people experience at some point each day, but long-term stress has a significant effect on overall health. Chronic stress can lead to:
- Disabling anxiety
- Depression
- Digestive problems
- Headaches
- Heart disease
- Insomnia
- Memory impairment
For some people, anxiety becomes a way of life – one that can lead to more serious medical problems. The American Psychiatric Association claims that stress and anxiety disorders make up the most common psychiatric problems globally. The current treatments involve drug therapies designed to counteract the effect of neurotransmitters that create the stress response, hopefully, reducing levels and improving patient outcomes.
Drug and talk therapy doesn’t work for everyone, though, which is why these scientists decided to look beyond pharmacological treatments and counseling. There is more than enough evidence to prove a link between neurological and digestive disorders, so the answer might not be in attempting to regulate neurotransmitter levels. It might be found in the manipulation and balancing of gut microbiota, instead.
Previous studies have shown that probiotics may help reduce stress. A study presented at the Society of Neuroscience in Chicago showed that male participants who took probiotic bacteria for one month felt less stressed. The tests also showed they had lower levels of cortisol, a stress hormone, in their blood, validating that claim. The conclusion is that certain strains of Lactobacillus exert a positive effect on anxiety and reduce the stress response.
The Zebrafish Study
In other to figure out whether probiotics could help reduce stress levels, the researchers gave zebrafish doses of Lactobacillus, bacteria often used in probiotic products, to see how they reacted. The second group of fish was used as a control and they were not dosed with Lactobacillus.
As part of the study, they stressed some of the fish in each group while not stressing the others. The goal was to figure out if the metabolic pathways associated with stress changed in any way in the probiotic group. Zebrafish have predictable reactions to stress, which helped the scientists validate that these fish did actually experience anxiety. A stress zebrafish will stay near the bottom of the tank, whereas, the fish at the top are experiencing less anxiety.
After completing the testing phase, they measured the genes associated with stress to predict how a probiotic would affect the fish’s behavior. What they found was dosing the zebrafish with probiotic bacteria did change the gene expression linked to stress pathways in the fish. In other words, probiotics may very well help soothe anxiety in humans as proven by the zebrafish.
Of course, this one study based solely on zebrafish is hardly enough to draw definite conclusions but it does look promising, especially when placed alongside other research showing how probiotics can help reduce stress.
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