Dopamine is one of the essential neurotransmitters in the brain. Its action is limited to the brain; it acts as a chemical messenger throughout the body. Dopamine stimulates the cardiovascular system's work and is responsible for cognitive abilities, coordination of movements, and even feelings. Here, we will try to explain how vital dopamine is in the human body.
Image Credit: Magdalena Osial
Dopamine as neurotransmitter
Our brain permanently sends messages to control the whole body. Breathing, heart beating, walking, eating, loving, missing, and everything our body does depends on this amazing organ. The brain is like a captain of the aircraft deciding about the destination or the travel.
All decisions, from muscles shrinking to the practical tasks that we perform, are dependent on our body's chemical compounds. Some of them work as messengers linking the brain and spinal cord to muscles, organs, and glands. These compounds are called neurotransmitters [1]. They are transported between neurons, one by one, every single second. Neurotransmitters transmit an electrical signal, which contains information, chemically between neurons and in this way to the central nervous system.
Dopamine is probably the most known neurotransmitter. It can be found in the retina or at the olfactory nerve, but mostly in our brain's substantia nigra [2]. This small molecule has a significant influence on our behavior. It acts as our body reward system, and its dysfunctions are associated with addiction. In the brain, it plays many roles, including movement, motivation, and reinforcement of behavior.
Several drugs such as cocaine, marijuana, methamphetamine, and heroin hijack dopamine signaling. They enhance the release of the neurotransmitter into the synaptic cleft. The excessive dopamine molecules bind to the receptors repeatedly, and the cell is overstimulated [3].
Dopamine as a hormone
Along with other chemical compounds like serotonin (happiness hormone) [4,5], oxytocin (the bonding hormone) [5], and endorphins (happiness hormones) [5,6] — it plays a vital role in how happy we feel. In addition to our mood, dopamine also affects movement, memory, and focus. It causes you to stay awake, desire, seek out, challenge yourself as well.
Healthy levels of dopamine drive us to seek and repeat pleasurable activities. In contrast, higher or lower levels can have adverse physical and psychological impacts.
Multiplicative dopamine's role
Dopamine is a crucial factor in many processes in our body and mind [7]. It is well known that it motivates to fight for the reword [8]. Did you know that dopamine has something in common with Romeo and Juliet from Shakespeare's drama? The very intimate and cherished relationship between the two lovers was driven by dopamine [9]. It is also responsible for negative feelings, and it is involved in switching emotions like fear and euphoria [10].
Dopamine helps to obtain a balance between a potential reward and a potential threat. Its release facilitates a fear memory formation, which links a traumatic event to a particular situation [11]. Its connection with such extreme emotions may be the reason why dopamine disorders can result in drug addiction, schizophrenia, and other phobias involving anxiety and fear.
Dopamine disorders
When we have low dopamine levels, we can manifest reduced alertness, problems with concentration, less motivation and enthusiasm, poor coordination, and even movement difficulties. What conditions cause a low level of dopamine? Dopamine plays a vital role in Parkinson's disease [12], a degenerative disorder that mostly affects the nervous system's coordination and motor functions. The symptoms include rigid muscles, slowed movement, tremor of limbs, or balance problems. There are some cases of people with Parkinson's disease who were taking drugs to reduce some dopamine. Surprisingly, they developed the symptoms of schizophrenia [13]. Sleep disorders also seem to be dopamine-dependent [14].
Moreover, dopamine is associated with reward and pleasure, so stimulating its pathways may introduce some addictions like gambling [15]. Conditions associated with low dopamine levels are also depression and dopamine transporter deficiency syndrome, called dopamine transporter deficiency syndrome, and infantile parkinsonism-dystonia. This rare syndrome affects a child's ability to move their body and muscles [16].
When we have the opposite situation, i.e., the high level of dopamine, you will feel like being on the top of the world, at least for a while. And what next? We do not have good news for you. If this condition continues and the dopamine level increases, it may cause mania, hallucinations, and delusions. Too much dopamine can result in obesity, neurological disorders like schizophrenia [13] or ADHD [17,18].
Summary
Dopamine is a molecule that is involved in physiological and neurological functioning. It contributes to mood, motor function, memory, cognition, feeling pleasure, and even our decision making. This tiny group of atoms influences our choices and desires. Its too little release in the brain can lead to Parkinson's disease or even mental disorders. Whether we want it or not, this molecule drives our brain. It shows that chemistry rules everything.
This paper is a joint work of Julia Lawinska (Faculty of Chemistry, University of Warsaw), Agnieszka Pregowska (Institute of Fundamental Technology Research), Magdalena Warczak (Institute of Physical Chemistry, Polish Academy of Sciences), and Magdalena Osial (Faculty of Chemistry, University of Warsaw) as a part of the Science Embassy project. Image Credit – Magdalena Osial.
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