Most times in the media and medical journals, dopamine, a catecholamine neurotransmitter associated with many psychiatric diseases, is often referred to as the reward or “feel-good” molecule. This may no longer be entirely true because a new study by Erin Calipari, an assistant professor of pharmacology, and a postdoctoral fellow in his lab, Munir Gunes Kutlu, have shown that just as the level of dopamine increases in pleasurable stimulus, it may also be increased by a stressful stimulus.
Dopamine has been a very critical molecule in our body, and for a long time known to be an important influencer in many psychiatric ailments. This discovery is expected to trigger a reevaluation of the true role of dopamine in the cause and treatment of these diseases.
The lead researcher, who is also a faculty member at the Vanderbilt Brain Institute and the Center for Addiction Research, insinuated that in the science world, though dopamine is identified to be essential in learning and memory, its exact function in the brain is not yet detailed.
What was found
A common suggestive theory, the reward prediction error theory, deduce that dopamine is an indicator for imminent rewards, and a tracker of the errors we make when aiming at getting rewards. However, a fresh study funded by the National Institutes of Health grants, and some other philanthropic institutions resulted in explaining that the RPE theory is not true in all the cases, by demonstrating that rewarding, as well as a stressful stimulus, will cause an increase in dopamine levels in the brain. Furthermore, the research revealed that dopamine is not even a feel-good hormone at all, it only helps to encrypt all significant life events, and surges irrespective of the beneficial or harmful outcome of each event.
A partner to this research includes the vice-chair of biochemistry and molecular medicine at UC Davis- Prof. Lin Tian, who used advanced technologies to examine novel changes in dopamine release with a wide array of neurobehavioral changes. The researcher then analyzed the data using machine learning and optogenetic manipulations.
More research is needed
Before this discovery, the entire science community believed, that all drugs of abuse facilitate the release of dopamine by neurons. This fanned the flames that dopamine was the reward molecule that induces appetitive behaviors. In contrast, this new research has established a model substantiating a more complex role of dopamine in the reward system and will instigate us to revisit the previous model of addiction founded solely on the dopamine-reward architecture.
After this, what next?
The outcome generated a new behavioral model that, according to Calipari, shows “accurate prediction of the behavioral impact of optogenetic perturbations of dopamine release.” This new knowledge has updated our information on dopamine and will incite authors and publishers to review the functions of dopamine in the central nervous system.
Professionally. we believe this new knowledge will influence every step in the management of several psychiatric illnesses. Scientists now have a clearer view of the impact of every minute change in dopamine levels on our behavior. The clinical application of this is that, for instance, in Parkinson’s disease where dopamine is believed to be deficient in the substantia nigra, we could in the future, develop models that can adequately titrate dopamine alone or with some other neurotransmitters to get a lasting remission with minimal extrapyramidal effects.
Having realized that dopamine also surges in events of a stressful stimulus, it has become clearer that in psychosis, which for long have been treated with dopamine antagonists, we may develop treatment models that will take the imbalance in other neurotransmitters into consideration.
The same model will also be applied in the management of depression and anxiety, where scientists have considered only the influence of the deficiency or excesses of dopamine and serotonin in the pathogenesis of these psychiatric ailments.
With this discovery, we hope to have a better understanding of the functions of this decisive neurotransmitters as it is implicated in a vast majority of psychiatric diseases, ranging from Parkinson’s to depression, anxiety, schizophrenia, etc. Understanding the effect of dopamine opulence or deficit will be key in the next phase of the diagnosis and evidence-based treatment of these diseases.
Subsequently using this new framework will also enhance the treatment of drug addiction as pertains to the role of dopamine.