The brain and the gut

The brain and the gut communicate with each other, and we are finding out more about this every day.

Many mood disorders, such as anxiety, depression, now have well-established links to functional GI disruptions. Not surprising, diet has also been shown to influence the gut microbiome’s impact on cognitive function

In rats, we have found that you can make an inactive, sad rat happy and active by changing its gut bacteria, and likewise, you can make a happy, healthy rat reserved and inactive by giving it the bacteria of a depressed rat.

The gut-brain axis transforms information via the vagus nerve from food to feelings. Once eaten, digested food particles enter the small intestine, which is covered with a velvety layer of villi. Each villus is lined with a single layer of epithelium. This layer is made up of different cell types.

One of them, the enteroendocrine cell, is unlike the others. It is our gut sensor. In addition to communicating through hormones, we discovered that enteroendocrine cells also synapse with nerves, including the vagus nerve. We call those enteroendocrine cells synapsing with nerves neuropod cells. They sense and react to their environment. They sense mechanical, thermal, and chemical stimuli such as nutrients or bacterial by-products in the gut lumen.

Inside neuropod cells, signals from stimuli are converted into tiny electrical pulses.

These pulses propagate via synapses onto the efferent neuron of the vagus nerve.

Vagul neurons carry the sensory information to the brain stem, linking the signals generated inside the small intestine to the brain.

The neuropod cell connection with the vagus nerve serves as a conduit for food in the gut to influence brain function within seconds.

This connection is also a potential channel for gut pathogens to access the brain.

This new knowledge is a foundation for designing therapies to treat disorders related to altered gut-brain signalling.