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 One gene closer to regenerative therapy for muscular disorders
01.06.2017 | Cincinnati Children's Hospital Medical Center

nachricht The gut microbiota plays a key role in treatment with classic diabetes medication
01.06.2017 | University of Gothenburg

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: Can we see monkeys from space? Emerging technologies to map biodiversity

An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.

Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...

Im Focus: Climate satellite: Tracking methane with robust laser technology

Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.

Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...

Im Focus: How protons move through a fuel cell

Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.

As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...

Im Focus: A unique data centre for cosmological simulations

Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.

With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...

Im Focus: Scientists develop molecular thermometer for contactless measurement using infrared light

Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine

Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Plants are networkers

19.06.2017 | Event News

Digital Survival Training for Executives

13.06.2017 | Event News

Global Learning Council Summit 2017

13.06.2017 | Event News

 
Latest News

Quantum thermometer or optical refrigerator?

23.06.2017 | Physics and Astronomy

A 100-year-old physics problem has been solved at EPFL

23.06.2017 | Physics and Astronomy

Equipping form with function

23.06.2017 | Information Technology

VideoLinks
B2B-VideoLinks
More VideoLinks >>>