If you’ve read that bacteria in our guts influence our moods and have wondered how that works, here’s a new clue towards solving this piece of the recently enlivened mind/body axis puzzle.
THE NEUROTRANSMITTERS GABA & GLUTAMATE
The amino acid called GABA (Gamma Aminobutyric Acid) is the principal INHIBITORY neurotransmitter in the mammalian central nervous system, sending chemical messages through the brain and nervous system and helping regulate communication between brain cells.
GABA’s chief role is to reduce the activity of nerve cells. It plays an important role in behavior, cognition, and how we respond to stress. Research suggests that GABA helps control fear and anxiety when neurons become overexcited. Below normal GABA levels in the brain have been linked to depression, anxiety, sleep disorders, and schizophrenia.
Pharmaceuticals called benzodiazepines bind to the same receptors as GABA, mimicking GABA’s natural calming effects. Examples of popular benzodiazepines for anxiety and insomnia are Valium (diazepam) and Ativan (lorazepam). They slow down the body’s central nervous system and cause sleepiness. (Konkel, 2015)
Glutamate (also called L-glutamate or glutamic acid)) is another important amino acid neurotransmitter released by nerve cells in the brain. It is involved in most aspects of normal brain functioning, including cognition, memory and learning. It is the major mediator of EXCITATORY signals in the mammalian central nervous system. (Danbolt, 2001)
GABA & GLUTAMATE IN BALANCE
Calming GAMBA restrains the release of excitatory glutamate. So you can see that a balance between GABA and glutamate production is needed for proper functioning. It’s a Goldilocks situation: The brain needs to release just the right amount of both GABA and glutamate. Too much or too little of one or the other causes problems.
IT TURNS OUT THAT A TYPE OF BACTERIA IN THE GUT LIVES ON GABA
Researchers have now observed gut bacteria consuming the brain chemical GABA. They found that a type of recently discovered gut bacteria, called KLE1738, can survive and reproduce only if it has GABA molecules to feed on. The researchers tried providing KLE1738 with other types of neurotransmitters but the bacteria couldn’t survive on anything but GABA. Without GABA, these bacteria die.
This is an important clue about how our gut bacteria influence our mood. “GABA acts by inhibiting signals from nerve cells, calming down the activity of the brain, so it’s surprising to learn that a gut bacterium needs it to grow and reproduce. Having abnormally low levels of GABA is linked to depression and mood disorders, and this finding adds to growing evidence that our gut bacteria may affect our brains.” (Coghlan, 2016)
An earlier experiment, in 2011, demonstrated that a different type of gut bacteria, Lactobacillus rhamnosus, dramatically altered GABA activity in the brains of mice as well as affected how well they responded to stress.
When the researchers surgically removed the vagus nerve, the communication pathway between the gut and the brain, the effect on the mice disappeared – more evidence on how gut bacteria influence the brain. (Coghlan, 2016)
The research team, led by Philip Strandwitz at Northeastern University in Boston, is now searching for other gut bacteria that consume or even produce GABA. They plan to test their effect on the brains and behavior of animals. Such work may eventually lead to new treatments for mood disorders like depression or anxiety.
“Due to this unique growth requirement, we provisionally name KLE1738 Evtepia gabavorous. Using growth of E. gabalyticus as an indicator, we then identified novel GABA producing bacteria from the gut microbiome. Reduced levels of GABA are associated with depression, and we found fewer GABA producers in a human cohort of depressed individuals. By modulating the level of GABA, microbial producers and consumers of this neurotransmitter may be influencing host behavior.” (Strandwitz et al, 2016)
Researchers are just at the beginning of looking into the many ways the gut microbiome influences, if not regulates, many bodily processes and how unbalance in the gut microbiome eventually leads to poor health.
This finding of a dependence of a type of gut bacteria on the neurotransmitter GABA doesn’t mean you should start yourself on one of the GABA supplements you’ll find for sale online. But do stay tuned! Neurotransmitters and specific microbes may become the treatment of choice for mood disorders – or, even better, for preventing mood disorders in the first place.
Keep your gut microbiome health, keep your body healthy.
Danbolt, N.C. (2001). Glutamate as a Neurotransmitter – An overview. Center for Molecular Biology & Neuroscience, The Neurotransporter Group – Dynamics of extracellular transmitter amino acids. See: http://neurotransporter.org/glutamate.html
As human animals we’re born as bodies with big powerful brains sitting up top in our heads. Our culture teaches us to value what goes on in the brain over what takes place in the rest of the body. Many of us learn to believe information generated by our brains and more or less ignore information available from the rest of the body – until something goes wrong down there.
And there’s so much that can go wrong from this disconnected, out of balance way of living. We then see a doctor to try to fix the symptoms of our ailment with medicines or surgery.
The way too many of us live – staying mostly up in our heads with little idea of our feelings and our true needs, all information generated by our guts:
The way we’re meant to be – brain and gut connected in constant communication:
The human gastrointestinal tract:
YOU HAVE TWO BRAINS – ONE RESIDES IN YOUR HEAD AND ANOTHER VERY IMPORTANT ONE LIVES IN YOUR GUT
We’re used to thinking of the brain in the head as the body part that’s running the show but, in fact, we also have a second brain. It resides in our digestive tract.
Parts of the enteric nervous system (the gut brain) and their functions:
A BRIEF COURSE ON OUR TWO BRAINS (Hardin, 2014 A-C)
On average, the human brain, the seat of all our thinking, contains 86 billion neurons engaged in transmitting information to and from the rest of the body.
The human enteric nervous system (the gut) contains 100 million neurons – about 1000th the number in the human brain and about equal to the number in the human spinal cord.
The autonomous nervous system of the gut allows it to work independently of the brain.
Our guts make more independent decisions for us than any other part of the body.
The gut’s endocrine signaling to the entire body is quite elaborate. Communication from our gut-dwelling microbes to the brain affects our emotions, motivation, cognition, memory and behavior.
Just like our thinking brain, our gut brain is also able to learn and remember.
In the lowest, most primitive part of our brains, a neural network called the basal ganglia is constantly evaluating the outcomes of our every behavior, extracting decision rules: ‘When I said that, it worked out well.’ ‘When I did this, bad things happened.’ And so on, like a tireless experimental scientist tasked with guiding us wisely through our lives.
The basal ganglia in the brain store our accumulated life wisdom. But when we are faced with a decision, it is the brain’s verbal cortex that delivers our thoughts about it, often drowning out the wisdom accumulated inside the basal ganglia’s storehouse.
And the most interesting part: The basal ganglia area is so primitive it has NO CONNECTION to the verbal cortex so it can’t share its knowledge in words – but its connections to the gut are plentiful. The basal ganglia area tells us what is right or wrong for us as a GUT FEELING.
So trust your gut, your felt sense, your intuition – not what comes to you in words from your brain!
Nearly every brain-regulating chemical found in our skull brains is also found in our gut brains. This includes major neurotransmitters (serotonin, dopamine, glutamate, norepinephrine and nitric oxide), brain proteins called neuropeptides, major immune system cells, a class of the body’s natural opiates (enkephalins), and even benzodiazepines (the family of psychoactive chemicals found in drugs such as Valium and Xanax).
The gut has opiate receptors much like the brain. Drugs such as morphine and heroin attach to opiate receptors in the brain and also in the gut, causing constipation. Both brains can be addicted to opiates.
Our emotions are greatly influenced by chemicals and nerves inside the gut. Most of us know Prozac as a best selling anti-depressant pharmaceutical. In 1971, when Eli Lilly was developing the drug, they expected it would become a treatment for high blood pressure or obesity.
Prozac works by increasing brain levels of serotonin, a neurotransmitter that produces feelings of well-being. Serotonin also affects sleep, appetite and aggression.
Known side effects of Prozac include nausea, diarrhea, insomnia, and a lowered sex drive – clear evidence of a gut-brain interaction.
90% of the body’s serotonin is located in the gut, where it regulates intestinal movements. Only 10% is synthesized in the central nervous system, where it serves many functions – including mood regulation, appetite, sleep, and the cognitive functions of memory and learning.
I’ve noticed as a psychotherapist that people’s voices relax and become lower pitched when they’re speaking their gut truths and get tenser and higher pitched when they’re saying what they think.
I can’t tell you the number of times I’ve asked somehow how they feel about something and am instead told how they think they feel. Not so useful.
Makes you realize how important it is for those two brains to communicate with each other – and how mistaken we are when we look to the brain in the head to tell us how we feel and what we need.
As Joan Rivers always said:
So how can you improve the communication between your gut and your brain? Here’s an exercise to try.
To help you spend less time in your head and more time in your body – and find it easier to go back and forth between them
Picture a lovely old circular stone staircase, maybe one winding down inside a medieval castle tower.
Imagine the top of the staircase is the brain up in your skull. Its steps lead down to the GI tract down in your gut.
Stand quietly for a moment up at the top of the staircase breathing slowly, letting your eyes look down a few steps. What color are they? What kind of texture do they have?
Notice the old stones the make up the stairs and walls. What color are they? What kind of texture do they have?
What’s the quality of the light inside the staircase?
Is it quiet in this staircase?
What emotions do you feel?
What bodily sensations do you notice?
Slowly step down to the second stair. Stand there a moment, breathing slowly and deeply, looking around.
Slowly step down to the third stair. Stand there a moment, breathing slowly and deeply, looking around.
Continue slowly down the other stairs, pausing between breaths on each stair.
If you can’t pause between breaths yet, rest for a few breaths on each stair before moving on.
Slowly descend the whole staircase in this manner observing what you see and what you’re feeling along the way, emotionally and sensations in your body.
When you reach the bottom of the staircase, spend a few easy breaths down there, in your gut. What do you see down there? What sensations do you feel?
When you’re ready, turn around and slowly walk back up the staircase to your brain in this same manner, noting what you see and how you’re feeling along the way.
When you reach your brain again, spend a few easy breaths up there. What do you see up there? What sensations do you feel?
Do you notice anything that’s different from the last time you were up there at the start of this walk? How’s your breathing?
Don’t worry if you’re unable to move down from the top step when you first try this exercise. Can you let yourself just be where you are on your staircase, breathing and looking around? Without chastising yourself?
Eventually, you’ll find you’re able to move further down toward your gut, which will be happy to greet you whenever you arrive.