Bacteria In the Gut May Affect the Brain

Bacteria and Brain
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Could the bacteria lurking in your gut influence your brain? According to an international team of researchers, studies in mice suggest that gut bacteria may have an impact on adult behavior.

Gut bacteria may affect brain development

The research team, composed of Dr. Martin Hibberd from the Genome Institute of Singapore and colleagues from the Karolinska Institute and Stockholm Brain Institute, evaluated the behavior and gene expression in two groups of mice. One group was raised with normal bacteria (microorganisms) and the other was raised in a bacteria-free environment.

Mice raised without exposure to bacteria behaved differently than those raised with normal microorganisms, which suggests gut bacteria has an effect on the brain. Specifically, adult mice raised in a germ-free environment were more active and displayed more aggressive or risky behaviors than mice exposed to microorganisms.

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Researchers noted that when the non-exposed mice were introduced to normal bacteria very early in life, they developed the behaviors seen in mice that had been raised with microorganisms from birth. When the scientists conducted gene profiling in the brain, they identified genes and pathways involved in learning, motor control, and memory impacted by a lack of gut bacteria.

The study is important because it suggests that during a period in early development, “gut microorganisms affect the brain and change the behavior in later life,” according to Dr. Diaz-Heijtz from the Stockholm Institute. The study noted that “gut microbiota may also be able to modify expression of risk genes or be part of mechanisms that alter cognitive functions observed in patients with gastrointestinal diseases.”

Hibberd added that the work can lead to a “new and exciting understanding of how humans might benefit from our interaction with microbes.” Thus, we may come to understand how the bacteria in our gut affect our brain.

SOURCE:
Diaz Heijtz R et al. Proceedings of the National Academy of Sciences of the USA 2011 Jan. DOI: 10.1073/pnas.1010529108

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