Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

SSRI antidepressants involve dopamine as well as serotonin signaling

07.04.2005


Researchers have discovered that antidepressant drugs such as Prozac not only affect levels of the neurotransmitter serotonin in the brain, but also "hijack" dopamine signaling as well--causing it to launch serotonin signals. Their findings offer new insight into how Prozac and other "selective serotonin uptake inhibitors" (SSRIs) work and how they might cause problems in patients taking them.



SSRIs perform their antidepressant function by increasing the concentration of serotonin in the signaling junctions, called synapses, between neurons. This increase alleviates the deficiency of serotonin that causes depression.

As their name indicates, SSRIs prevent uptake of the serotonin after it has performed its task as a chemical messenger that enables one neuron to trigger a nerve impulse in a neighbor. SSRIs prevent this uptake by inhibiting the action of the molecular cargo carriers called transporters that recycle serotonin back to the neuronal storage sacs called vesicles.


Now, however, Fu-Ming Zhou (presently at the University of Tennessee) and colleagues at Baylor College of Medicine have revealed that SSRIs can have more complex effects on neurotransmitter traffic in the brain than just altering serotonin levels. They found that higher serotonin concentrations caused by SSRIs can "trick" transporters of another key neurotransmitter, dopamine, into retrieving serotonin into dopamine vesicles. Dopamine transporters have a low affinity for serotonin, but the higher serotonin levels result in its uptake by the dopamine transporters, found the scientists.

As a result, the normal dopamine-triggered firing from such neurons, in essence, launches two different types of neuronal ammunition, causing "cosignaling."

The researchers were led to study the role of dopamine signaling in SSRI action by previous evidence that dopamine was involved in depression and in the function of antidepressants in the brain. They studied the nature and machinery of serotonin and dopamine signaling by treating mouse brain slices with fluoxetine (Prozac) and other chemicals, and analyzing the effects on the dopamine-signaling machinery.

The relatively inefficient, slow process of "hijacking" of dopamine transporters by serotonin during SSRI treatment could explain why it takes many days of treatment before antianxiety effects are seen, suggested the researchers.

Also, they wrote that their findings may explain why treatment of children with fluoxetine can induce depressive symptoms in adulthood. The researchers wrote that, since serotonin plays a vital role in neuronal development, disruption by fluoxetine of the normal serotonin levels during development could be responsible for such behavioral abnormalities.

They also theorized that such corelease of dopamine and serotonin caused by SSRIs could explain cases of a "potentially life-threatening serotonin syndrome" caused by such situations as dietary overload of serotonin precursors in people taking SSRIs.

The researchers wrote that the relationship between dopamine and serotonin signaling "is likely vital for normal behavior and for the pathology that can be treated with SSRIs." The brain area involved, the ventral striatum, "is critically involved in the neuronal processes of reward and emotional functions." Thus, they wrote, enhanced participation of the striatal dopamine system in serotonin signaling during treatment with SSRIs "may contribute to the therapeutic efficacy of SSRIs."

Heidi Hardman | EurekAlert!
Further information:
http://www.cell.com

More articles from Health and Medicine:

nachricht Genetic differences between strains of Epstein-Barr virus can alter its activity
18.07.2019 | University of Sussex

nachricht Machine learning platform guides pancreatic cyst management in patients
18.07.2019 | American Association for the Advancement of Science

All articles from Health and Medicine >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Better thermal conductivity by adjusting the arrangement of atoms

Adjusting the thermal conductivity of materials is one of the challenges nanoscience is currently facing. Together with colleagues from the Netherlands and Spain, researchers from the University of Basel have shown that the atomic vibrations that determine heat generation in nanowires can be controlled through the arrangement of atoms alone. The scientists will publish the results shortly in the journal Nano Letters.

In the electronics and computer industry, components are becoming ever smaller and more powerful. However, there are problems with the heat generation. It is...

Im Focus: First-ever visualizations of electrical gating effects on electronic structure

Scientists have visualised the electronic structure in a microelectronic device for the first time, opening up opportunities for finely-tuned high performance electronic devices.

Physicists from the University of Warwick and the University of Washington have developed a technique to measure the energy and momentum of electrons in...

Im Focus: Megakaryocytes act as „bouncers“ restraining cell migration in the bone marrow

Scientists at the University Würzburg and University Hospital of Würzburg found that megakaryocytes act as “bouncers” and thus modulate bone marrow niche properties and cell migration dynamics. The study was published in July in the Journal “Haematologica”.

Hematopoiesis is the process of forming blood cells, which occurs predominantly in the bone marrow. The bone marrow produces all types of blood cells: red...

Im Focus: Artificial neural network resolves puzzles from condensed matter physics: Which is the perfect quantum theory?

For some phenomena in quantum many-body physics several competing theories exist. But which of them describes a quantum phenomenon best? A team of researchers from the Technical University of Munich (TUM) and Harvard University in the United States has now successfully deployed artificial neural networks for image analysis of quantum systems.

Is that a dog or a cat? Such a classification is a prime example of machine learning: artificial neural networks can be trained to analyze images by looking...

Im Focus: Extremely hard yet metallically conductive: Bayreuth researchers develop novel material with high-tech prospects

An international research group led by scientists from the University of Bayreuth has produced a previously unknown material: Rhenium nitride pernitride. Thanks to combining properties that were previously considered incompatible, it looks set to become highly attractive for technological applications. Indeed, it is a super-hard metallic conductor that can withstand extremely high pressures like a diamond. A process now developed in Bayreuth opens up the possibility of producing rhenium nitride pernitride and other technologically interesting materials in sufficiently large quantity for their properties characterisation. The new findings are presented in "Nature Communications".

The possibility of finding a compound that was metallically conductive, super-hard, and ultra-incompressible was long considered unlikely in science. It was...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

2nd International Conference on UV LED Technologies & Applications – ICULTA 2020 | Call for Abstracts

24.06.2019 | Event News

SEMANTiCS 2019 brings together industry leaders and data scientists in Karlsruhe

29.04.2019 | Event News

Revered mathematicians and computer scientists converge with 200 young researchers in Heidelberg!

17.04.2019 | Event News

 
Latest News

Heat flow through single molecules detected

19.07.2019 | Physics and Astronomy

Heat transport through single molecules

19.07.2019 | Physics and Astronomy

Welcome Committee for Comets

19.07.2019 | Earth Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>