What are neurotransmitters and what do they do?
Neurons are cells within the nervous system and communicate by discharging a small chemical messenger called a neurotransmitter.
Neurotransmitters are essentially chemical messengers that our body needs in order to function. Their job is to carry messages from one nerve cell to the next target cell. The next target cell can be another nerve cell, a muscle cell or a gland.
Neurons are either excitatory or inhibitory when they communicate. Excitatory neurons excite their target cells whilst inhibitory neurons inhibit their target cells.
Excitatory neurotransmitters are:
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Adrenaline, noradrenaline (flight or flight adrenal hormones)
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Dopamine (pleasure and reward)
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Serotonin (happy hormone)
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Acetylcholine (learning and memory hormone)
Inhibitory neurotransmitter:
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GABA (Gamma-aminobutyric acid). This is the only inhibitory neurotransmitter and is known for it’s anti-anxiety properties
Although each of the neurotransmitters is always excitatory or inhibitory, they can still have opposite effects. For example, if dopamine excites an inhibitory neuron pathway, it will exaggerate the inhibitory response.
If inhibitory neurotransmitter GABA acts on an inhibitory neuron pathway, then the result is excitation since the inhibition is being inhibited!
So in other words, there is a lot going on in our bodies and how our neurotransmitters are working will affect how we feel on a day to day basis.
Our brain not only needs to release the right kind of neurotransmitter but the right amount. For example, if you are driving and a pedestrian runs out in front of your car, your brain will release noradrenaline, one of the adrenal hormones released during stress.
It gets released so you can respond quickly to the stressor but it only releases enough that it doesn’t impact on your breathing and pulse rate.
Levels of noradrenaline are then topped up for the next time you might need it.
The neurotransmitter life-cycle involves:
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Synthesis – dependent on availability of substrates, cofactors, and environmental stimuli
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Signalling – by receptors, which can have a direct effect on a nerve cell or activate a secondary message cascade
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Transport – removal of neurotransmitters from the synapse back into to the cell for storage
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Metabolism – the breakdown of neurotransmitters and removal of metabolites
Let’s talk about some key neurotransmitters.
Serotonin
Serotonin is manufactured in the middle of the brain in an area called the raphe nuclei. It’s production is triggered by the activation of the tectum. We need adequate light for the tectum to be activated, which is why if people spend a lot of time indoors or the weather is dark and gloomy for months, we can suffer lower levels of serotonin production.
Low serotonin levels are associated with increased anger and aggression, depression, OCD, IBS, migraines, tinnitus, fibromyalgia, bipolar disorder and anxiety disorders.
Excess levels of serotonin have been associated with shyness, inferiority complex, nervousness, fear of being disliked and a desire for social connection but afraid to initiate it. However, these traits that are not always associated with excess serotonin.
Serotonin, also known as 5-hydroxy-tryptamine or 5-HT, is associated with well-being and is
popularly referred to as the ‘happiness neurotransmitter’.
The majority (about 90%) is made in the gut where it regulates gastrointestinal movements. The remainder is synthesised in the central nervous system (CNS) where, with melatonin, it affects mood, appetite and sleep. It also affects cognitive functions including memory and learning.
Symptoms of low serotonin:
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Feelings of depression
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Feelings of inner rage and anger
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Difficulty finding pleasure in life
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Feeling down when there is lack of sunshine/ cloudy and dull days
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Loss of pleasure in hobbies and interests
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Not enjoying your favourite foods
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Not enjoying friendships and relationships
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Unable to fall into deep, restful sleep
Symptoms of high serotonin:
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Anxiety, irritability or restlessness
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Bone loss
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High blood pressure
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Gut sensitivity or diarrhoea
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Carcinoid syndrome
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Headaches
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Fatigue
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Weight gain
Serotonin and Oestrogen
Excess serotonin can be associated with excess oestrogen. Oestrogen increases the activity of the serotonin receptor and increases overall serotonin in the brain.
This can also work the other way and low oestrogen levels can cause low levels of serotonin.
Postmenopausal women who don’t produce much oestrogen can be at risk of low serotonin levels. Low mood and poor mental cognition may be symptoms.
Serotonin levels can be impacted by nutrition and lifestyle factors such as protein intake
and exercise. There are many different triggers of imbalance, the most common being stress, inflammation, light exposure and genetics.
We can help serotonin production by ensuring we eat enough of the amino acid, tryptophan which is key to manufacturing serotonin.
We cannot make tryptophan in the body and so we need to make sure we are getting it through the food we eat. Foods such as chicken, shrimps, spinach, turkey, lamb, beef, liver, mushrooms, and salmon are all rich in tryptophan.
However, most of our diets will give us enough.
What can hinder the production is if the tryptophan can’t cross the blood-brain barrier.
Western diets are full of sugar and constantly fluctuating insulin and blood sugar levels can stop this transportation of tryptophan to the brain.
GABA
Gamma-aminobutyric acid (GABA) is an amino acid that functions as the primary inhibitory neurotransmitter for the central nervous system (CNS).
GABA slows down your brain by blocking specific signals in your central nervous system (your brain and spinal cord).
GABA is known for producing a calming effect. It’s thought to play a major role in controlling nerve cell hyperactivity associated with anxiety, stress and fear. GABA is also closely related to progesterone. In perimenopause, falling progesterone levels cause low levels of GABA.
It’s a good idea to get neurotransmitters in check before Perimenopause/menopause but it’s never too late!
GABA production is a byproduct of energy production in the brain, produced in the ‘GABA shunt’ (sounds like a dance doesn’t it?!).
When glucose is metabolised for energy, one of it’s byproducts, glutamate is converted into GABA and used when it’s needed for it’s calming effects.
Once used, it converts back into a substance that is then sent back into the energy production cycle.
Symptoms of GABA imbalance:
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Feelings of anxiousness or panic (for no reason)
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Feelings of dread
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Feelings of excitability and inner tension
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Restless mind
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Feeling overwhelmed for no reason
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Can’t switch off when you want to relax
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Worry about things you had never thought of before
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Focusing on lots of things all at once in a disorganised manner
Many people with GABA issues are also gluten intolerant. Gluten intolerance, coeliac disease and autoimmune diseases can trigger an autoimmune reaction against the enzyme responsible for making GABA (GAD – glutamic acid decarboxylase). The result is not enough calming GABA.
Blood sugar balance is also important. Hypoglycemia, insulin resistance and diabetes can lower glucose levels in the brain, overall energy production therefore falls and decreases GABA production.
Lack of oxygen in the brain can also be an issue. This could be because of anaemia or poor blood flow.
We should also be aware of toxins that can damage brain tissue and hinder the energy production cycle.
Some people will be genetically predisposed to poor GABA production. Taking a DNA test can reveal any gene variations and necessary action can be taken to manage how genes behave.
Melatonin
Melatonin is a hormone that your brain produces in response to darkness. It is secreted by the pineal gland located behind the eyes. Melatonin has diverse functions that regulate the circadian rhythm, energy metabolism, and the immune system. It also inhibits oxidative stress and participates in the ageing process.
Melatonin is also known as N-acetyl-5-methoxy-tryptamine and is also an antioxidant. It suppresses insulin which is not needed during sleep.
Healthy sleep is dependent on healthy melatonin activity however melatonin relies on serotonin for proper function. Serotonin is converted into melatonin in the pineal gland.
Melatonin is also one of the hormones which regulates female reproductive hormones , helping determine when menstruation begins, the frequency and duration of menstrual cycles and when menopause begins.
The conversion of serotonin to melatonin involves two enzymes: NAT and 5-HIOMT. These enzymes depend on methyl donors and the adrenal hormone, noradrenaline.
We often think of adrenal stress hormones as preventing sleep and this is true if we get chronically stressed but low levels will hinder the conversion of serotonin to melatonin and also prevent good sleep.
Symptoms of impaired melatonin activity:
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Moodiness, SAD
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Lethargy
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Migraines brought on by too much darkness or poor light
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Bipolar disorder and major depressive disorders
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Sleep disturbances
Melatonin and Cortisol
Another adrenal hormone that affects melatonin levels is cortisol. If cortisol levels become too elevated, melatonin levels drop. This is commonly seen in people with insulin resistance and they’ll often struggle with insomnia.
I talk more about the other neurotransmitters including Dopamine, Adrenaline and GABA in the extended version of this blog post available in The Female Food Club.
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