The Microbiome-Gut-Brain Axis
Tuesday, October 18, 2011
Have you ever noticed that you feel ‘sick to your stomach’ when you are nervous? Or have you ever had a ‘gut feeling’ about something? Well, a recent study on probiotics has added another potential piece to the gut-brain connection puzzle to help us understand how and why our emotions are so intimately involved with our digestive systems. A team of scientists in Canada looked at the effects of supplementation with Lactobacillus rhamnosus on both the brains and behavior of mice.
As most of you reading this blog probably know, probiotics are good bacteria that are specifically defined as live micro-organisms that, when administered in adequate amounts, confer a beneficial physiological effect on the host. The study in Canada elucidated a previously unknown benefit of these little bacteria. Apparently, supplementation with Lactobacillus rhamnosus significantly increased the number of GABA receptors in certain areas of the brain, reduced the amount of corticosterone produced by the adrenal glands and reduced certain anxiety and stress related behaviors in mice. Since this study was performed on mice, we cannot immediately assume that the results of this study are applicable to a human population but it is certainly a step in the right direction towards a randomized control trial with human subjects in the near future.
The main inhibitory (which can also loosely be described as the main anti-anxiety) neurotransmitter in the brain is GABA (gamma-aminobutyric acid). Anti-anxiety medications such as Xanax and Valium reduce anxiety by enhancing the effects of GABA in the brain. Since the Lactobacillus rhamnosus increased the number of GABA receptors in certain areas of the brain, the overall effect of supplementation was a decrease in anxiety levels. The researchers did not stop once they determined that the probiotics were affecting the number of receptors; they wanted to understand HOW the probiotics were affecting receptor expression. They hypothesized that the probiotics were somehow ‘communicating’ with the brain via the vagus nerve.
The vagus nerve, also known as Cranial Nerve Ten (CN X), is responsible for almost all parasympathetic stimulation in the body. Our autonomic nervous system has two parts that work in tandem – the sympathetic, or ‘fight or flight,’ portion and the parasympathetic, or ‘rest and digest,’ portion. During digestion it is the vagus nerve that slows the heart rate, decreases blood flow to the extremities, increases blood flow to the digestive tract and promotes digestion. To test their hypothesis, the researchers cut the vagus nerve just above the digestive tract in some of the mice. After the subdiaphragmatic vagotomies were performed, they determined that the positive changes that occurred as a result of probiotic supplementation were not seen in the mice without a vagus nerve innervating their digestive tracts. So, it does appear that their hypothesis was correct and the probiotics are somehow using the vagus nerve in the gut as a way to ‘communicate’ with and affect change in the brain. They point out that they do not understand the molecular mechanism by which the probiotics affect the vagus nerve but they hope that future studies will resolve the mystery.
The authors of the study state "it is worth noting that the majority of studies on the microbiome-gut-brain axis are rodent-based", and future validation of the role of this axis in modulation in behavior is now warranted. Nonetheless, our current studies offer the intriguing opportunity of developing unique microbial-based strategies for the adjunctive treatment of stress-related psychiatric disorders.’ At the very least, everyone should be taking a probiotic during and after taking a prescription antibiotic to replenish their highly beneficial population of good bacteria. If you want to increase your intake of probiotics, they can be found in supplements and in fermented foods such as kombucha, yogurt and kimchi. Yum!!
Laura Firetag ND Student Bastyr University
References:
1. Bravo, Javier. "Ingestion of Lactobacillus Strain Regulates Emotional Behavior and Central GABA Receptor Expression in a Mouse Via the Vagus Nerve ." Proceedings of the National Academy of Sciences of the United States of America. 108.38 (2011): 16050-55. Print.
Labels: anxiety, axis, gut health, lactobacillus, probiotic
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4 Comments :
Are you pregnant?..follow me
Auracacia
This one is seriously unseen wealthy information.
Regards
Pure Acai
The GUT Brain Axis interections effects the memory-based immune adaptive system that responds to each new encounter with the microbial world gene-expression on the basis of past interactions.
Therefore the adaptive immune system evolved in humans not only to mount defenses against microorganisms but because of their need to recognize and manage the symbiosis with the many complex communities of beneficial microbes in particulat to those that live in the intestinal tract . In particular the enteric microbiota interacts with the gut-microbiome to form essential relationships that govern metabolic homeostasis.
see : http://www.b2match.com/meet4lifesciences/profiles/1768
Therefore the regulation of the microbiome–gut–brain axis is essential for maintaining both symbiosis and the relative homeostasis of gut metabolic functionality, and this includes tha memory processes of enteric brain (ENS) but also are inclusive of the bi-directional signalling with the central brain (CNS)
Therefore the ability of gut microbiota to communicate with the two brains
(ENS<--> CNS) and thus modulate their activity of neurotransmission is emerging as an exciting concept in health and disease prevention. . The enteric microbiota interacts with the host to form essential relationships that govern homeostasis.
Despite the unique enteric bacterial fingerprint of each individual ( e.g Microbiome) , there appears to be a certain composition balance that confers a health gut benefits. It is, therefore, reasonable to note that a decrease in the desirable gastrointestinal bacteria will lead to deterioration in gastrointestinal, neuroendocrine and/or immune relationships and ultimately metabolic and immunologic diseases. Therefore, studies focusing on the impact of enteric microbiota of the host and also to the central nervous system interactivity are essential to scientific understanding of the influence of this complex gut-brain axis system.
Paolo Manzelli
see http://www.academia.edu/4026192/5_Manzelli_GUTBRAINAXIS
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