January 8, 2014 Sophie Langley
Using a mouse model, US researchers have linked neurodevelopmental symptoms similar to those seen in autism spectrum disorder (ASD) patients to changes seen in the bacteria in the animals guts.
ASD is diagnosed when individuals exhibit characteristic behaviours that include repetitive actions, decreased social interactions, and impaired communication. Many individuals with ASD also suffer from gastrointestinal (GI) issues, such as abdominal cramps and constipation.
Using the co-occurrence of brain and gut problems in ASD as their guide, researchers at the California Institute of Technology (Caltech) were investigating a potentially transformative new therapy for autism and other neurodevelopmental disorders. The research, which was published online in the December issue of the journal Cell, is the first to demonstrate that changes in the gut bacteria can influence autism-like behaviours in a mouse model. The gut microbiota the community of bacteria that populate the human GI tract previously has been shown to influence social and emotional behaviour.
Traditional research has studied autism as a genetic disorder and a disorder of the brain, but our work shows that gut bacteria may contribute to ASD-like symptoms in ways that were previously unappreciated, said Sarkis K. Mazmanian, an author of the study and Professor of Biology at Caltech. Gut physiology appears to have effects on what are currently presumed to be brain functions, he said.
Study method
To study this gut-microbiota-brain interaction, the researchers used a mouse model of autism previously developed at Caltech in the laboratory of Paul H. Patterson, the Anne P. and Benjamin F. Biagginin Professor of Biological Sciences. In humans, having a severe viral infection raises the risk that a pregnant woman will give birth to a child with autism. Patterson and his lab reproduced the effect in mice using a viral mimic that triggers an infection-like immune response in the mother and produces the core behavioural symptoms associated with autism in the offspring.
In the new study, Professor Mazmanian, Professor Patterson and their colleagues found that the autistic offspring of immune-activated pregnant mice also exhibited GI abnormalities. In particular, the GI tracts of autistic-like mice were leaky, which means that they allowed material to pass through the intestinal wall and into the bloodstream. This characteristic, known as intestinal permeability, has been reported in some autistic individuals.
To our knowledge, this is the first report of an animal model for autism with comorbid GI dysfunction, said Elaine Hsia, a senior research fellow at Caltech and first author on the study.
Mice treated with probiotics
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Probiotics a potential treatment for autism?