Serotonin's Neural Activity Can Now Be Tracked in Real Time

Experts in the United States may have just found a way to make it easier for neuroscientists to figure out what causes depression and how the condition acts inside the human brain. This was achieved when experts created a tag that can be applied to a critically-important molecule.

According to Vanderbilt University investigators, the tag is applied to a protein that is very important for regulating the activity of the neurotransmitter serotonin. The latter plays the most important role in depression, and most antidepressants in some way act on its molecular pathways.

Depression, anxiety disorders, and some personality disorders are oftentimes treated with a class of drugs called SSRI, or selective serotonin re-uptake inhibitors, which includes known names such as Lexapro, Zoloft, Prozac and Cipralex, among many others.

Now that the team can tag serotonin transporter proteins, they can finally study in great detail where the neurotransmitter binds to nerve cells. The work is bound to at least refine existing drugs, if not spawn an entirely new class of antidepressants altogether.

It is very important to note here that scientists needed more than 10 years to develop the chemical tag, which is in fact just a quantum dot. These are clumps of matter whose excitons are thoroughly confined on all three axes, and which represent a step between semiconductors and discrete molecules.

The tiny fluorescent beads are 10,000 times smaller than the width of a human hair, and can be attached to the transport protein seamlessly. By using advanced microscopic techniques, researchers can then track serotonin as it moves around among neurons, PsychCentral reports.

In addition to playing a significant role in the onset and development of depression, the neurotransmitter is also involved in regulating aspects such as mood, appetite and sleep. Therefore, research conducted in those fields could benefit from the new capability as well.

“If you are interested in mental health, then serotonin transporters are an ideal subject,” the Vanderbilt Jack and Pamela Egan Chair of Chemistry, Sandra Rosenthal, PhD, explains. She led the study with the Allan D. Bass professor of pharmacology and psychiatry, Randy Blakely, PhD.

“In the past, we have been limited to snapshots that show the location of transporter molecules at a specific time. Now we can follow their motion on the surface of cells in real time and see how their movements relate to serotonin uptake activity,” chemistry graduate student Jerry Chang concludes.