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  • Writer's pictureKim May

What is a neurotransmitter?

Many of us use or come to depend on the effects of drugs without quite understanding how they work. All drugs (well the good ones anyway) affect our brain and are thusly referred to as psychoactive drugs.

A psychoactive drug is one that crosses the blood brain barrier and subsequently cause changes in our mood, perception, and brain function. This includes everything from coffee to heroin.

Neurotransmitters can be thought of as chemical information systems between neurons. Once the message is received (synapse) the neurotransmitter is stored in the neuron. Psychoactive substances tend to block, mimic, lessen, expand, or bind to these neurotransmitters.

Yes, but IS a neurotransmitter?!

Neurotransmitters are molecules joined by a chemical bond that acts a unit. A neuron receives, processes, and sends out new messages. You can think of the neuron as the computer and the neurotransmitter as the email. While there are around one hundred identified neurotransmitters, there are a mere handful that are affected by psychoactive substances (at least that have been identified so far).

8 neurotransmitters worth knowing

1. Acetylcholine. Considered one of the main neurotransmitters, it excites neurons in the brain and many other parts of the body. Acetylcholine stimulates muscles and allows for movement, including muscle contraction. Additionally, it influences how the brain processes information, affecting arousal, motivation, and mood and assists in regulating certain bodily functions such as heart rate, digestion and reflexes like vomiting and coughing.

There are two major acetylcholine receptors; they are muscarinic (certain types of psychedelics) and nicotinic (nicotine products).

Acetylcholine related psychedelics include belladonna and deadly nightshade, ibogaine (found in the Amanita mascaria mushrooms), and the iboga plant. These drugs block acetylcholine which slows the heart and helps to form memories. However, all acetylcholine related drugs can be lethal at doses that are not much higher than recreational doses.

Nicotine stimulates the nicotinic acetylcholine receptor, which are widely distributed on nerve cells throughout the brain, so nicotine effects a variety of brain structures. Overall, it has the effect of releasing dopamine and exciting nerve cells, which helps make using tobacco very reinforcing. Studies have shown that nicotine increases areas of the brain associated with memory and other mental functions.

2. Anandamide and 2AG. Our brain provides its own cannabinoid receptors and Anandamide and 2AG are the compounds that activate those receptors.

Anandamide (derivation of Sanskrit for bliss) is involved in regulating mood, memory, appetite, and pain. It is also one of the brain’s endogenous (meaning within) cannabinoids. 2AG (a shortening of a waaaay too long proper name) was the second endogenous cannabinoid that was identified. Its presence is 170x greater than anandamide.

When we add exogenous (from the outside) cannabinoids, the delicate balance and concentration gets ramped up, causing the feeling of being high.

3. Dopamine. The most important neurotransmitter involved in reward processing. Dopamine plays a significant role in the motivation to obtain the pleasure. Dopamine is responsible the addiction potential of a substance (or action, like gambling) due to the positive reinforcement of pleasurable feelings.

Regulation of dopamine plays a key role in our mental and physical health, and impacts brain processes responsible for controlling movement, motivation, emotional response, and the ability to experience both pleasure and pain.

Overtime, we need more of a substance (or action) to get the same pleasurable feeling, which gives way to tolerance which is a critical component of addiction.

4. Endorphins. Ah, these are the brain’s endogenous opioids. They are responsible for suppressing pain and creating feelings of euphoria. They are released during stress, relaxation, and pain. Opioids bind to the opioid receptors (the mu receptor is the primary one) in the brain thereby mimicking the role of endorphins.

One of the significant downsides of prolonged opioid use is that our brain’s endogenous opioid system shuts down, sensing that we are getting plenty of exogenous opioids.

5. GABA. An amino acid that works as a neurotransmitter and inhibits neurons. Also known as the brain’s sedative, calming down brain activity like brakes. Benzodiazepines (Xanax, Klonopin, etc.) act through an effect on GABA.

6. Glutamate. Also, an amino acid, but it is excitatory (stimulating nerve cells to fire) and is related to learning, memory, and attention. Alcohol decreases the supply of glutamate.

7. Norepinephrine. Acts as both a hormone and a neurotransmitter. When on the job as a neurotransmitter, it helps regulate arousal, dreaming and moods. Also known as the “fight or flight chemical” it arouses the body when in danger. This is the gas pedal in the brain. When acting as a hormone, it increases blood pressure, constricts our blood vessels, and increases heart rate (our sympathetic nervous system).

Stimulants increase the amount of norepinephrine in the brain. Amphetamines not only release norepinephrine and dopamine into the synapse, but they also block the reuptake. Cocaine does not release more; it only blocks reuptake making our own supply more readily available.

8. Serotonin. It has a significant role in emotional disorders (think depression, impulsive behavior) and is also related to sex drive, appetite, and sleep. There is also some influence over cognitive functions.

MDMA (ecstasy or molly) greatly increases levels of serotonin, which creates feelings of wellbeing. The synapses become flooded with serotonin, which is an excitatory neurotransmitter. This temporarily depletes the brain’s supply of serotonin, and it can take time to achieve homeostasis again.

Know your drugs

As Patt Denning and Jeannie Little state in their book, Over the Influence, “Just say know to drugs.” They go on to say: “Know what they are, know how they work, know what you want, and know your limits.”

Understanding why we are drawn to certain substances and what happens when we put them in our body gives us tools to better understand ourselves and assist us in making more informed decisions.

If you need more information or feel that your substance use is causing you problems, Substance Use Therapy is here.

Whatever you are facing, you don’t have to face it alone.


Denning, P., & Little, J. (2017). Over the Influence: The Harm Reduction Guide to Controlling Your Drug and Alcohol Use. The Guilford Press.

Erickson, C.K. (2007). The Science of Addiction. W.W. Norton & Company.

Kuhn, C., Swartzwelder, S., & Wilson, W. (2019). Buzzed: The Straight Facts about the Most Used and Abused Drugs from Alcohol to Ecstasy. W.W. Norton & Company.

Lembke, A. (2021). Dopamine Nation. Dutton.

About the Author:

Kimberly May, LPC-S, LMFT is a therapist at Substance Use Therapy in Austin, TX. Kimberly works with individuals, couples and families whose lives have been affected by substance use. By utilizing a harm reduction framework, Kimberly works effectively with people in any stage of use. In addition to substance use, she works with other issues such as anger, burn-out, anxiety and grief. Contact today to schedule a no-charge, 30 minute, in-person consultation. *Note: telephone and telehealth sessions are currently available.

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