Neurotransmitters (A complete guide)

What are Neurotransmitters?

Neurotransmitters are chemical messengers in the brain that relay information to other neurons, or nerve cells.

They are molecules that transmit messages between neurons and neurons to muscles by our nervous system. 

Communication happens in the synaptic cleft, which is the space between two neurons.

Most neurotransmitters are small amine molecules or amino acids. Neurotransmitters can exert different effects on neurons; they can be: 

·      Excitatory

·      Inhibitory

·      Modulatory

Excitatory neurotransmitter:

A neurotransmitter that triggers an increase in the membrane potential of the postsynaptic neuron is known as an excitatory neuron.

To explain membrane potential in an easy to understand way, think of it as a number let’s say -80.

When positively charged molecules enter the neuron, the voltage, or membrane potential of the neuron becomes more positive, let’s say to -60.

Glutamate is the major excitatory neurotransmitter in the central nervous system.

Inhibitory neurotransmitter:

A neurotransmitter that triggers a decrease in the membrane potential of the postsynaptic neuron is known as an inhibitory neuron.

Gamma aminobutyric acid (GABA) is the main inhibitory neurotransmitter in the central nervous system. 

Modulatory neurotransmitter:

These are also referred to as neuromodulators and are capable of affecting a large number of neurons at the same time.

Examples of neuromodulators are enkephalins and endorphins. 

Our brain needs neurotransmitters to perform many necessary functions, including the regulation of:

–       Heart rate

–       Sleep cycle

–       Breathing

–       Digestion

–       Mood 

–       Concentration

–       Muscle movement

How do neurotransmitters work?

In order to send a message throughout the body, neurons need to communicate with one another.

However, typical neurons are not physically connected with each other. At the end of every neuron, there is a tiny gap which is known as a synapse.

A neurotransmitter has to cross the synaptic cleft, or space between two neurons, in order to exert its effects.

When an electric signal reaches the end of a neuron, it triggers the release of small sacs called vesicles that contain the neurotransmitters.

These sacs spill their contents into the synapse where the neurotransmitters move across the synapse toward neighbouring cells.

These cells contain receptors where the neurotransmitters can trigger changes in cells.

After the release, neurotransmitters cross this gap and bind to the receptor on the other neuron. 

If the neurotransmitter causes enough of an increase in the resting potential of a neuron, an electrical signal called an action potential can be transmitted down the cell, which will then cause the release of neurotransmitters again.

Remember those numbers we talked about?

If the membrane potential of the cell goes from -80 to -55, an action potential might be triggered depending on the type of neuron. 

What happens when neurotransmitters bind to receptors? 

Receptors are located in the plasma membrane of a neuron, which means they reside on the neuron’s surface.

There are different types of receptors that are specific for different neurotransmitters.

Once the neurotransmitter binds, the receptors can either open to let positive or negative charge into or out of the neuron, or initiate a signalling cascade.

Signaling cascades are chemical responses that initiate the expression of certain genes, growth of cells, and cell death.

Receptors are a very important part of our nervous system because they convey signals. 

What are conventional neurotransmitters? 

Conventional neurotransmitters are stored in vesicles and get released into the synaptic cleft.

There are two categories of conventional neurotransmitters:

–       Small molecule neurotransmitters

–       Neuropeptides

What are unconventional neurotransmitters?

Non-conventional or unconventional neurotransmitters are classified into two main categories:

×        Neurodegeneration

×        Neuroprotection

What are some of the brain’s major neurotransmitters?

Neurotransmitters play an important role in daily life.

Scientists do not know exactly how many neurotransmitters exist, but more than 50 distinct chemical messengers have been discovered.

Here are seven major neurotransmitters listed below along with their functionality.

1.    Acetylcholine

Acetylcholine (Ach) is found in sensory neurons and plays an important role in the normal function of human muscles.

It triggers our skeletal muscles to contract. It also plays a role in our sleep cycle. 

Key facts:

·      The main function of acetylcholine is to stimulate muscle contraction and regulate the sleep cycle.

·      It is an excitatory neurotransmitter except in the heart, where it acts as an inhibitory neurotransmitter.

·      It is released by postganglionic neurons of the sympathetic nervous system.

2.    Norepinephrine

Norepinephrine is also called noradrenaline (NE). In the human body, it is secreted by most postganglionic nerves and acts to stimulate arousal.

High concentrations of NE in the brain can lead to sleeping difficulties.

Conditions related to norepinephrine include many disorders like anxiety disorders, mood disorders and Alzheimer’s disease.

Many symptoms related to these disorders are directly attributable to norepinephrine dysfunctionality.

Key facts:

·      It is an excitatory neurotransmitter.

·      Produced by adrenal glands, brainstem and released into the bloodstream. 

3.    Serotonin

Serotonin, sometimes abbreviated as 5-HT, is a neurotransmitter that controls many aspects of our daily functioning including mood, appetite, and sleep.

Dysfunction in the 5-HT system has been implicated in the pathogenesis of depression.

Insufficient amounts of serotonin may play a role in anger issues and even suicidal tendencies.

Typical antidepressants work by increasing the amount of serotonin available in the synapse. 

Key facts:

·      There are many different types of serotonin receptors, and the effects are usually inhibitory

·      It is released mainly from neurons in the brainstem.

·      The main function of serotonin is to regulate the body temperature, emotions and the sleep cycle. Check out the effects of yelling in the brain.

4.    Dopamine

Dopamine (DA) is known as the “reward” neurotransmitter in the brain. It is also involved in movement.

Many neurodegenerative diseases such as Parkinson’s disease and psychiatric disorders such as drug addiction are related to alterations in the DA system in the brain. 

Key facts:

·      It is both excitatory and an inhibitory neurotransmitter.

·      It is released from the substantia nigra and the ventral tegmental area of the brain.

·      It stimulates the secretion of growth hormone and inhibits unnecessary movements.

5.    Histamine

Key facts:

·      It is an excitatory neurotransmitter and released from mast cells and cells of the stomach mucosa.

·      Regulates local immune responses

·      In an animal model, it has been shown to change blood-brain barrier permeability, which causes increases in neuroinflammation. 

6.    Glutamate

Glutamate is the main excitatory neurotransmitter in the brain and balances out the inhibitory effects of GABA.

Dysfunctions in glutamate neurotransmission can cause epilepsy and other cognitive disorders.

Key facts:

·      An excitatory neurotransmitter and released from sensory neurons. 

·      The main function of glutamate is to regulate the central nervous system, learning process and memory.

7.    GABA

GABA stands for gamma-aminobutyric acid. It is the main inhibitory neurotransmitter in the brain and is produced by neurons in the cortical areas of the brain.

GABA is derived from glutamate. It is targeted in the treatment of insomnia, anxiety and other related problems.

Key facts:

·      Inhibitory neurotransmitter

·      The main function of GABA is to reduce neuronal excitability in the nervous system.

·      It is involved in regulating many functions and is widely distributed in the brain.

What happens when neurotransmitters do not work correctly?

These are the few things that can go wrong with neurotransmitters in the brain: 

–       Neurotransmitters may be reabsorbed.

–       Neurotransmitters may be deactivated.

–       Too many neurotransmitters may be released.

–       Neurons might not manufacture enough neurotransmitters.

What are the causes of neurotransmitter dysfunction? 

Neurotransmitters control all functions of the human body.

They are such strong chemical messengers that regulate various physical, mental and emotional processes.

If there is an imbalance in neurotransmitters, it may lead towards mental disorders like anxiety and depression. 

There are many causes of neurotransmitter dysfunction, and some of them are highlighted below:

Stress:

Prolonged periods of stress can cause the imbalance of neurotransmitters. 

Poor diet:

In the human body neurotransmitters are made from proteins and other minerals which are known as “cofactors”.

Thus, a healthy diet is required to maintain the level of neurotransmitters.

If your nutrition is poor and you do not think about what you eat, then it can cause severe imbalance due less quantities of essential vitamins and minerals.

Genetic factors:

Problems with metabolism and digestion which can be genetic may also hamper your cells’ ability to produce neurotransmitters.

Toxic substance:

Toxic substances like pesticides, heavy metals and other drugs can damage the neurons, which are responsible for the production of neurotransmitters. 

Hormones:

Changes in hormonal levels can cause neurotransmitters imbalances.

Drugs that influence neurotransmitters:

Drugs are capable of changing the effects of neurotransmitters, which can improve the symptoms of some diseases.

Generally, drugs can be agonists or antagonists.

Agonists increase the effects of a specific neurotransmitter, whereas antagonists block the effects of the neurotransmitter.

Drugs can also have direct and indirect effects on neurotransmitters.

There are many drugs that influence the actions of neurotransmitters, and some drugs have adverse effects:

×        Heroin

×        Cocaine

×    Nicotine 

Testing and treatment

Neurotransmitters are the masters of our brain’s communication system, and they influence everything from movements of the body to our mood.

The nervous system is a highly complex interconnected network.  

There are certain tests that can determine if there are imbalances in your neurotransmitters.

Laboratory tests can provide precise details about which neurotransmitter is deficient in the body using blood or a urine sample.

These tests are beneficial for diagnosing disorders and other deficiencies.

They can also help monitor the effectiveness of certain medications.

Nutrient therapy is the most common treatment for increasing the level of neurotransmitters because it has no side effects.

To increase the level of neurotransmitters naturally, incorporate these 10 tips into your daily routine:

1.    Eat a lot of proteins

2.    Eat less saturated fats  

3.    Consume probiotics 

4.    Exercise often

5.    Listen to music

6.    Sit in sunlight

7.    Sleep well

8.    Meditate

9.    Consider supplements

10.                  Reduced intake of toxic substances

These tips are helpful in maintaining proper levels of neurotransmitters and can help reduce anxiety, elevate mood, improve focus and concentration and gradually increase the levels of dopamine, norepinephrine and epinephrine.

Side Note: I have tried and tested various products and services to help with my anxiety and depression. See my top recommendations here, as well as a full list of all products and services our team has tested for various mental health conditions and general wellness.

 Frequently asked questions (FAQs) about neurotransmitters? 

1.    What are the 7 major neurotransmitters?

Acetylcholine, norepinephrine, serotonin, dopamine, GABA, glutamate, endorphin

2.    What is the role of a neurotransmitter? 

Neurotransmitters are chemical messengers within the brain and are used by the nervous system to transmit messages between neurons or from neurons to muscles.

3.    What causes an imbalance in neurotransmitters?

Prolonged periods of stress and certain substances such as caffeine, alcohol, and nicotine can deplete neurotransmitter levels and lead to imbalances.
 
In this article, we discussed what neurotransmitters are, how they work in the brain, different types of neurotransmitters, and what happens when neurotransmitter levels are imbalanced. 

Want to learn more about neurotransmitters? Try these recommended readings!

Better Living Through Neurochemistry – A guide to the optimization of serotonin, dopamine and the neurotransmitters that color your world

James Lee provides an in depth overview of what neurotransmitters are, what they do in your brain and body, and how to boost levels.

This book also explains how to know when certain neurotransmitters are depleted. 

References

What are neurotransmitters? Queensland Brain Institute. November 9th, 2017. 

The Brain from Top to Bottom. McGill University. 2020  

What are neurotransmitters. Medical News Today. 2020. 

Can a Neurotransmitter Imbalance be Causing Your Mood Problems? Integrative Psychiatry. 2020 

Olivia Levine (neuroscientist, neuroscience PhD candidate) 

Was this post helpful?

[Sassy_Social_Share type="standard"]