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Fluorescence in Medicine | Malaria | Atabrine | SSRI Research | Goldwater Memorial Hospital | National Heart Institute

SSRI Research

NIH scientist Dr. Julius Axelrod used the SPF to measure tiny amounts of serotonin in the blood. Serotonin was first isolated from the blood in 1948 and identified as being present in the central nervous system. The body system involving serotonin is known to affect mood, emotion, sleep, and appetite. One cause of depression is an abnormal function of the serotonin transmitter system. Therefore, a drug that builds the concentrations of serotonin should alleviate the symptoms.

Dr. Axelrod's research, for which he won the Nobel Prize in 1970, led to the development of SSRI (selective serotonin re-uptake inhibitor) drugs such as Prozac, Zoloft, and Paxil.


How does an SSRI work?
The brain is made up of neurons, which are interconnected brain cells. Messages travel along these cells. When a message reaches the end of a neuron, it has to jump a gap (called a synapse) to the next one. To do this, the neuron releases tiny amounts of a chemical (a neurotransmitter) into the gap between the nerve cells. Ideally, a nerve impulse starts in the new nerve, and thus the message gets from one nerve to the next. In order for the original nerve to recover and get the next message, it needs to replace its stocks of the neurotransmitter in the original neuron so it is ready to send the next message. The "healthy" body thus takes the neurotransmitter back into the originating neuron (this is called "re-uptake").

In the case of depression, certain neurotransmitters such as serotonin are lacking, so they cannot be taken back in full to the originating neuron and therefore cannot send the next message. SSRIs slow down the process of returning serotonin to the end of the neuron it comes from (they inhibit the process of re-uptake). This makes it more likely that enough serotonin will build up to set off the impulse in the next neuron. Therefore, SSRIs work by allowing the body to make the best use of reduced amounts of serotonin.

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