PUBLIC RELEASE DATE:

9-Oct-2014

Contact: Mark Wheeler mwheeler@mednet.ucla.edu 310-794-2265 University of California - Los Angeles @uclanewsroom

People with autism spectrum disorder often experience a period of accelerated brain growth after birth. No one knows why, or whether the change is linked to any specific behavioral changes.

A new study by UCLA researchers demonstrates how, in pregnant mice, inflammation, a first line defense of the immune system, can trigger an excessive division of neural stem cells that can cause "overgrowth" in the offspring's brain.

The paper appears Oct. 9 in the online edition of the journal Stem Cell Reports.

"We have now shown that one way maternal inflammation could result in larger brains and, ultimately, autistic behavior, is through the activation of the neural stem cells that reside in the brain of all developing and adult mammals," said Dr. Harley Kornblum, the paper's senior author and a director of the Neural Stem Cell Research Center at UCLA's Semel Institute for Neuroscience and Human Behavior.

In the study, the researchers mimicked environmental factors that could activate the immune system such as an infection or an autoimmune disorder by injecting a pregnant mouse with a very low dose of lipopolysaccharide, a toxin found in E. coli bacteria. The researchers discovered the toxin caused an excessive production of neural stem cells and enlarged the offspring's' brains.

Neural stem cells become the major types of cells in the brain, including the neurons that process and transmit information and the glial cells that support and protect them.

Notably, the researchers found that mice with enlarged brains also displayed behaviors like those associated with autism in humans. For example, they were less likely to vocalize when they were separated from their mother as pups, were less likely to show interest in interacting with other mice, showed increased levels of anxiety and were more likely to engage in repetitive behaviors like excessive grooming.

Link:
UCLA study finds link between neural stem cell overgrowth and autism-like behavior in mice

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