Neurotransmitters - What Are They, How Are They Tested, and Why It May Be Causing Your Anxiety or Mood Swings

The role of neurotransmitters in the human body is quite challenging to understand, and science is still studying them. Science knows many neurotransmitters, but perhaps there are more waiting to be discovered.

These are chemicals that nerve cells use to communicate. They use it to communicate within themselves and other tissues. Thus, propagation of nerve signals is only possible with the help of neurotransmitters. These neurotransmitters also make muscle contraction possible and play a vital role in releasing various hormones.

Neurotransmitters are not only present or released by nerve cells. They are also produced by other body cells and can influence the working of neurons. 

What are neurotransmitters

Simply said, these chemicals make the working of nerve cells possible. However, their role is not limited to nerve cells as they play an important role in the contraction of muscles, autonomous nervous system, mood, hormone levels, etc. Thus, neurotransmitters can affect almost every body's function.

Any change in neurotransmitters' levels may have a widespread impact on health. Sometimes these changes are local, limited to certain parts of the nervous system, and in other cases, more universal.

Thus, for example, deficiency of dopamine in substantia nigra causes Parkinson's. 

However, understanding the impact of more subtle imbalances of neurotransmitters is relatively challenging. It may not result in disease but cause mood swings, fatigue, increased anxiety, hormonal changes in the body, increased risk of chronic disorders, etc.

How they play a part in your mood

Before we look at the role of some of the neurotransmitters in mood, it is essential to understand that all neurotransmitters have multiple functions. Very often, deficiency or excessive release of these neurotransmitters in specific brain centers would have different effects. Thus, low dopamine is implicated in mood issue but also cause fatigue, issues with muscle movement, and more.

Here we look at some of the neurotransmitters that are vital for maintaining a good mood:

• Dopamine is a neurotransmitter of pleasure and plays an important role in the reward pathway. Thus, its release provides pleasure, but its deficiency causes depression. Therefore, it plays an important role in substance addiction, as people seek drugs to increase dopamine's release and thus experience pleasure¹.
• Serotonin – is another vital neurotransmitter that plays a central role in mood regulation. It is perhaps more important in regulating mood than any other neurotransmitters. That is why drugs used to manage depression mainly work by increasing serotonin levels in certain brain centers².
• Norepinephrine is vital to maintaining mood, concentration, and energy levels. It means that its lower levels cause depression and an inability to focus on things. Many medications used to treat depression, like monoamine oxidase inhibitors, work by increasing its levels and influencing other neurotransmitters³.
• Glutamate – is an excitatory neurotransmitter that can affect various brain centers. Its optimal level is essential for maintaining mood, memory, cognition, learning abilities, and more. Unfortunately, chronic stress often causes depletion of this neurotransmitter and thus mood disorders⁴.

Of course, this list is not comprehensive by no means, but these are some of the most important and well-known neurotransmitters that affect mood. In addition, neural imbalances of these neurotransmitters are often implicated in the development of various brain disorders.

What low or high levels mean

Any imbalance in neurotransmitters is not good and may cause a range of disorders. It means that both high and low levels are bad for health. Neurotransmitter imbalances cause eating disorders, sleeping disorders, changes in metabolism, depression, anxiety, fibromyalgia, migraine headaches, behavioral changes, etc. It means that over-production or low production of neurotransmitters can affect almost every health parameter.

Thus, a low level of dopamine in various brain centers may cause depression, fatigue, lack of concentration, changes in muscle function, Parkinson's, and more⁵.

On the contrary, high dopamine may also cause problems like aggressive behavior, poor impulse control, substance addicting, ADHD, binge eating, and more.

A high level of dopamine may alter sensation and make you feel on top of the world. Many street drugs work by increasing dopamine and thus altering the senses. 

Similarly, take the example of serotonin. Its low-level causes depression, sleep troubles, anxiety, and other mood-related issues.

On the other hand, a high serotonin level may cause rigidity, fever, seizures, diarrhea, and other symptoms.

The different neurotransmitter pathways and their roles

There are hundreds of neurotransmitter pathways in the brain with thousands of varying functions or roles. Doctors are still discovering and understanding their mechanisms. 

There are various brain centers controlling different body functions and pathways through which information flows in the brain. Moreover, these pathways can be modulated in many ways.

For example, the role of dopaminergic pathways is well known in Parkinson's disease⁶. In addition, dopaminergic pathways play a vital role in the consolidation of good memories, pleasure, addiction, and more. Thus, it has numerous functions in the body.

Similarly, changes in the serotonergic pathway may cause different mood disorders. It has an important role in anxiety disorders and similar mood disorders⁷.

How are they tested?

There could be numerous ways of testing neurotransmitter levels or checking the working of various pathways. For example, changes in brain MRI may indicate issues with specific pathways. Similarly, doctors may even use nuclear medicine to visualize the activity of various brain centers.

However, a relatively simpler way is to look for the neurotransmitters or their metabolites in the urine. It may not be as accurate as those used in clinical studies, but this method is more accessible and practical for broader use. In this method, specialists may either look for a particular neurotransmitter or its metabolites in the urine, thus providing pretty accurate estimates of their levels.

References

• Juárez Olguín H, Calderón Guzmán D, Hernández García E, Barragán Mejía G. The Role of Dopamine and Its Dysfunction as a Consequence of Oxidative Stress. Oxid Med Cell Longev. 2016;2016:9730467. doi:10.1155/2016/9730467
• Michely J, Eldar E, Martin IM, Dolan RJ. A mechanistic account of serotonin's impact on mood. Nat Commun. 2020;11(1):2335. doi:10.1038/s41467-020-16090-2
• Moret C, Briley M. The importance of norepinephrine in depression. Neuropsychiatr Dis Treat. 2011;7(Suppl 1):9-13. doi:10.2147/NDT.S19619
• Pal MM. Glutamate: The Master Neurotransmitter and Its Implications in Chronic Stress and Mood Disorders. Frontiers in Human Neuroscience. 2021;15. Accessed April 18, 2022. https://www.frontiersin.org/article/10.3389/fnhum.2021.722323
• Franco R, Reyes-Resina I, Navarro G. Dopamine in Health and Disease: Much More Than a Neurotransmitter. Biomedicines. 2021;9(2):109. doi:10.3390/biomedicines9020109
• Albanese A, Altavista MC, Rossi P. Organization of central nervous system dopaminergic pathways. J Neural Transm Suppl. 1986;22:3-17.
• Lesch KP, Zeng Y, Reif A, Gutknecht L. Anxiety-related traits in mice with modified genes of the serotonergic pathway. European Journal of Pharmacology. 2003;480(1):185-204. doi:10.1016/j.ejphar.2003.08.106