The 3 Channels of Gut-Brain Communication, Part 1
Our gut talks with our brain using three channels. First up is the nervous system.
“Nature is everywhere gothic, not classic. She forms a real jungle, where all things are provisional, half-fitted to each other, and untidy.” —William James
New discoveries about the gut-brain axis continue to illuminate how gut microbes affect our mood. Even after years of working on the concept, scientists are still amazed at how tiny microbes can alter the workings of the mighty human brain.
Since they can’t escape the dangerous germs coating our planet, animals have adopted their own set of beneficial microbes to fight, starve, and outcompete the pathogens. Like all important biological functions, there are backups and backups to the backups. And so, for our friendly microbes, our body has created at least three different avenues of communication.
Each communication channel has its charms. Some are fast and potent, while others are gentle and languorous. If you’ve ever had food poisoning, you know about fast and potent. When your gut senses an attack of nasty microbes, you receive an urgent directive to find a bathroom, pronto. On the other hand, when you enjoy a warm bowl of oatmeal, your mood may reflect the laid-back consensus of contented gut microbes.
The three main communication channels between your brain and your gut include your nervous system, your immune system, and your endocrine system. The circulatory and lymphatic systems also play supporting roles, but these first three are dominant. Nevertheless, each system interacts with the others, making it difficult to discuss any of them in isolation. William James was right; nature is untidy.
Each of the gut-brain channels has its own unique chemical language, but because they also communicate with each other, they need to have some signaling molecules in common. Here are the three main systems and the chemicals they use to chat.
The nervous system
The nervous system relays information to, from, and throughout your brain. It communicates using chemicals called neurotransmitters. Its communication style is fast and point-to-point, but short-acting. The vagus nerve is the primary boulevard for this neural traffic.
Your gut is encased in a tube of nerves called the enteric nervous system. It contains as many nerve cells as your spinal cord, and in honor of its size and importance, it is often called the second brain. A big part of its job is to control peristalsis, the rhythmic movement of muscles that squeeze your food from one end to the other. But your gut lining also contains cells that can sense the environment and send messages to the brain. These can be notices of satiety or more ominously, about pathogens and food poisoning.
Incredibly, the microbes in your gut produce neurotransmitters identical to those that your brain uses to communicate from one cell to another. These are partly for microbes to talk to each other, but also to talk to us, their host. The neurotransmitters include dopamine and serotonin, two of the most important chemicals involved in psychiatry. This is thus an immediate channel of communication for your gut microbes to let your brain know what’s going on down under. It can quickly alter your mood.
This gut-brain connection makes it clear why you should be solicitous of your microbial happiness. Treat your microbes right, and they will be on the front line of defense against pathogens. Abuse them, and they can make you miserable on short notice.
Next week, we will continue with the next channel of the gut-brain axis, the immune system. As always, be sure to subscribe (it’s free!) so you don’t miss it!
References
Anderson, S. C., Cryan, J. F., Dinan, T. The Psychobiotic Revolution. Washington D.C.: National Geographic.
Can’t wait for part 2!