Some Interesting Research on the Gut and the Brain

The significance of the gut microbiome has been touched on before on this blog, but there is some interesting and relevant research that might change the way you think about what goes on between your brain and your gut bacteria!

In one experiment, scientists observed two sets of mice: one group had had gut microbes, and the other group of mice were kept in sterile bubbles and had no microbes. The ones without microbes had less inhibition and were more prone to taking risks and exploring their environment. This meant more wondering about in open fields, and this reckless behaviour goes against years of mouse evolution and will likely lead them to getting eaten. These microbe-free mice also had memory-related defects. The two types of mice were put through some tests: they were given 5 minutes to explore two objects, and then the objects were removed for a while. One of the objects they’d seen was given back to them, along with a new one. The mice with the gut microbes only explored the new object and ignored the one they were familiar with, but the microbe-free mice paid the same amount of attention to both objects , behaving as if they’d completely forgotten about the object they’d just seen moments ago.

It was thought that this memory deficiency in the microbiota-free mice was caused by lower levels of Brain Derived Neurotropic Factor (BDNF). BDNF is a powerful protein important for learning and memory; it stimulates production of new brain cells and protects existing ones, and low levels of it are linked to depression and anxiety. So can your microbiome influence personality?

In 2011, a research group at McMaster University performed an experiment on two types of lab mice – one type were deemed anxious and withdrawn, and the other type were highly exploratory. They measured their extroversion by putting the two on a platform and seeing how long it took for them to explore the ledge and jump down (as expected, the anxious mice took longer). The researchers did a microbiota transplant between the mice and repeated the platform test – shockingly, the extroverted mice became timid and took far longer, with the previously anxious mice now unbothered by the ledge. Behaviour and anxiety changed depending on which microbes were living in their gut, and the newfound confidence was linked to more BDNF.

Serious changes in brain chemistry are moderated by specific microbes in the gut. Of course, this is all research based on rodents, but it still stands to show that the gut is essentially a drug factory pumping out different substances that affect the brain. Now that’s something to think about when taking your probiotics!




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