Yogurt bacterium plays role in alleviating depression symptoms in mice, UVa researchers find
A study at U.Va. found that lactobacillus - a probiotic bacteria commonly found in live-culture yogurt - can relieve some symptoms of depression in mice.
The finding is the latest in a string of studies linking gut flora with the brain that - if they stand up to scrutiny - could provide a new avenue of treatment for people with neurological disorders.
"The gut can influence many aspects of an organism's biology in general," said
U.Va. is one of many institutions across the country studying the "gut-brain" connection - the ways in which microorganisms in the digestive tract influence the brain and nervous system. Late last year, the lab reported that immune cells normally found in the gut also reside in the meninges - the membranes surrounding the brain and spinal cord.
In the future, doctors might be able to use this connection between the gut and the brain to help treat symptoms in a less invasive way, said
"The microbiome is such an important player in human biology and it's so easy to modify," he said. "You don't even need to take drugs."
Scientists still are learning the ways in which gut flora affect our overall health.
Future medical treatments could involve dietary changes and rely less on side effect-inducing drugs, Gaultier said.
Lactobacillus, the bacteria that played a central role in the U.Va. study, is commonly found in live-culture yogurt and used to treat diarrhea.
The research team at U.Va. found that the amount of lactobacillus present in mice affected their behavior.
Being subjected to stress lowered levels of the bacteria in the mice, which led them to show "depressive behavior," Marin said.
Their mood improved as soon as they were given food laced with lactobacillus. Scientists believe the bacteria are tied to kynurenine, a metabolic substance linked to depression. When levels of lactobacillus fell, levels of kynurenine rose, changing the subjects' moods.
The research team tested the effects of kynurenine directly on the mice and confirmed that injections of the substance could induce depressive behavior.
Human depression is a far more complex problem, Marin said, but the findings could provide a hint into some of the forces that affect people's moods.
"What causes depression - we're still trying to understand that," she said. "Until we know the cause, we can't talk about fixing the problem. We can talk only about relieving the symptoms."
The next step is a trial on human subjects. Gaultier said he wants to focus on multiple sclerosis patients.
Clinical depression is one of the most common symptoms of the disease, but the reason is still unclear.
Researchers currently are trying to find funding for the trials, which could take two years or more, Gaultier said.
"We are at the beginning," he said. "The idea is to see whether this translates to humans."