For decades, dopamine was presented to the odd public almost exclusively as “the pleasure molecule” or as the biochemical axis of addictions. However, neuroscientific research accumulated over the last twenty years paints a much broader and more nuanced picture: this neurotransmitter is, in reality, a silent coordinator of essential bodily functions ranging from motor maintenance to regulation of the immune system.
In this sense, it is valuable to offer a comprehensive look at the role of dopamine in the human organism, dispelling myths and highlighting its clinical and daily importance.
Motivation and learning engine
One of the most transformative contributions of recent neuroscience was distinguishing between dopamine and pleasure. Research led by neuroscientist Kent Berridge demonstrated that the dopaminergic system is more associated with wanting —the wanting, the anticipatory desire—that at likingthat is, to the sincere enjoyment of an experience. In other words: dopamine drives search, not satisfaction.
This distinction is better for understanding learning. The brain releases dopamine when it anticipates a reward, and adjusts that release depending on whether the prediction was correct or not. This mechanism, known as “reward prediction error,” is what spoils how we learn from experience: we reinforce behaviors that obtained better results than expected and abandon those that disappointed.
Dopamine and movement: the lesson of Parkinson’s
The importance of the dopaminergic system in maintaining motor control became tragically evident with the understanding of Parkinson’s. This neurodegenerative disease is characterized precisely by the progressive death of dopaminergic neurons in the substantia nigra, a brain region that makes up the so-called nigrostriatal system. The direct consequence is the loss of dopamine in the striatum, which results in tremors at rest, muscle rigidity, bradykinesia – slowness of movement. and difficulty initiating motor actions.
The standard treatment for decades has been levodopa, a dopamine precursor that can cross the blood-brain barrier, reaffirming the central role of this neurotransmitter in regulating movement. Without enough dopamine, the body literally shuts down.
Its presence beyond the brain
Although the role of dopamine is in the central nervous system, its presence is not limited to the brain. The gastrointestinal tract houses the so-called “enteric nervous system”, where dopamine participates in the regulation of intestinal motility. It is estimated that about 50% of the dopamine in the human body is composed in the intestine, although it cannot cross the blood-brain barrier, so it fulfills differentiated local functions.
Even more surprising: recent research indicates that cells of the immune system, such as T lymphocytes and dendritic cells, express dopamine receptors and are capable of synthesizing it. This suggests that the neurotransmitter plays a role in modulating immune responses, opening a promising line of research in autoimmune and inflammatory diseases.
When dopamine is missing or unbalanced
Deficits in dopaminergic activity are associated not only with Parkinson’s, but also with depression—particularly the symptoms of anhedonia and lack of motivation—attention deficit hyperactivity disorder (ADHD) and certain forms of psychosis. On the other hand, excess dopaminergic signaling, or its deregulation, is linked to schizophrenia and addictive disorders.
Balance is the key. Dopamine is neither good nor bad in itself: it is a signaling system whose effectiveness depends on the amount released, the available receptors, the speed of reuptake and the brain region involved. Altering any of these variables, whether due to illness, substances or repetitive behaviors, has consequences on multiple levels of well-being.
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