Gut-Organ Axes: The Gut-Brain Connection

I am very excited about this blog series! Over the next few weeks, we are going to cover gut-organ axes. We will start at the head of the animal end with the organs closest to the tail. That means this week we are starting with the gut- brain connection!

 

What is the gut-brain connection?

This connection serves as a bi-directional link where signals and metabolites can be sent between the brain and the gut. The gut-brain connection is one of the most extensively studied gut-organ-axes within all mammalian species.

Research has revealed that the microbes in the gastrointestinal tract (GIT) play a critical role within the brain of the animal. Including: brain development, neural processes, pain processes, the hypothalamic-pituitary-adrenal (HPA) axis, and animal behavior. Because of the broad impact on the brain, the gut-brain connection is becoming a tool with which we can modulate brain function, and ultimately animal health.

 

Communication Pathways

There are 3 different pathways known to serve as routes of communication for the gut-brain connection.

1. Immunoregulatory Pathway: the immune system interacts with the gut microbiota and affects the way cells signal each other and the regulation of inflammation.

2. Neuroendocrine Pathway: involves both the HPA axis and the central nervous system (CNS). The intestines of mammals serve as one of the largest endocrine organs in the body. There are over 20 different types od enteroendocrine cells found there. Microbes within the gut regulate the production of many neurotransmitters through the HPA axis and the CNS.

3. Enteric Nervous System (ENS): The ENS passes signals with the vagus nerve, which allows communication between the microbes and the brain. One example is when the toxic metabolites ammonia and D-lactic acid are fermented in the rumen, they can travel this route and negatively impact animal stress response and sleep quality. When we look at it the other direction, sensory neurons can send signals from the brain through the vagus nerve and CNS to control gut motility and hormone secretion.

 

Role of the gut-brain connection

Changes in the gut microbiota during an infection or during stressful events negatively impacts the brain and influences animal behavior. When the GIT is healthy then healthy brain function is promoted.

Research has shown that after stressful events such as weaning and transportation, there is an increase in cortisol, stress response related hormones from the pituitary gland, and signaling molecules that promote inflammation.  When select probiotics and prebiotics are added to the diet of ruminant animals the signaling of the HPA axis is prevented and the animal does not show the same increase in anxiety during stressful events.

 

Ultimately, the GIT microbiota impact animal behavior directly as well as overall health of the host. Feeding behavior is included in the processes affected. The microbial population in the GIT directly impacts the feed efficiency of livestock. Any increase in pathogenic bacteria results in an increase in sickness behavior which results in lower feed intake. Same is true in a bout of acidosis as there is a rapid change in the gut microbiota. 

Utilizing select pre and probiotics in our livestock production systems can help to alleviate negative signals being past back and forth from the gut to the brain.  MicroBasics utilizes highly researched and effective ingredients to promote healthy communication between the gut and the brain to influence overall animal health, well-being, and productivity. Check out available blends in our online store!