A quarterly publication of the Autism Research Institute

The Autism Research Review International is quarterly publication of the Autism Research Institute

Spring, 2016 | Number 2, Volume 30

Mouse study: Restoring one species of gut bacteria can correct social impairments

Researchers at Baylor University report that mice lacking one specific species of bacteria in their guts exhibit social deficits similar to those seen in autism, and that restoring this species can reverse some of their behavior problems. 

Noting that children of obese mothers are at higher risk for autism and that children with autism often suffer from gastrointestinal problems, Shelly Buffington and colleagues explored the possible relationship between gut microbes, obesity, and social behavior. The researchers first fed about 60 female mice a high-fat diet equivalent to eating fast food. They then bred the mice and weaned their offspring onto a normal diet. After a month, the offspring exhibited behavioral abnormalities including spending less time with their peers and failing to initiate social interactions. 

The researchers then compared the gut bacteria of these “fast food” mice to those of mice born to mothers fed a normal diet. Buffington reports that the differences were so consistent “that by looking at the microbiome of an individual mouse we could predict whether its behavior would be impaired.” 

Next, the researchers housed both groups of mice together so that they would acquire each other’s gut microbes by eating feces (a typical mouse behavior). As a result, the mice in the high-fat group quickly developed a normal microbiome. When this happened, their social behavior became more normal as well. Fecal transplant experiments involving mice with no gut bacteria (which also are socially impaired) were consistent with these results. 

Finally, the researchers determined that one specific bacterial species—Lactobacillus reuteri—was responsible for the behavioral deficits of the “fast food” group. “We found that treatment with this single bacterial strain was able to rescue their social behavior,” Buffington says. The researchers discovered that the mice deficient in this bacterial species exhibited a lack of synaptic potentiation in a key reward area of the brain in response to social interaction, and that providing them with the bacteria corrected this anomaly. They also note that Lactobacillus reuteri boosts levels of the hormone oxytocin, which plays a powerful role in social behavior. 

Senior study author Mauro Costa-Mattioli comments, “Other research groups are trying to use drugs or electrical brain stimulation as a way to reverse some of the behavioral symptoms associated with neurodevelopmental disorders—but here we have, perhaps, a new approach. Whether it would be effective in humans, we don’t know yet, but it is an extremely exciting way of affecting the brain from the gut.”


Citations

“Microbial reconstitution reverses maternal diet-induced social and synaptic deficits in offspring,” Shelly A. Buffi ngton, Gonzalo Viana Di Prisco, Thomas A. Auchtung, Nadim J. Ajami, Joseph F. Petrosino, and Mauro Costa-Mattioli, Cell, Vol. 165, June 16, 2016, 1762-75. Address: Mauro Costa-Mattioli, [email protected]

—and—

 “A single species of gut bacteria can reverse autism-related social behavior in mice,” news release, Cell Press, June 16, 2016.