Seratonin in Synapse


Serotonin is a molecule that Neuron 1 releases over time into the synapse (i.e., space between Neuron 1 and Neuron 2).  Serotonin is recycled back into Neuron 1 by Serotonin/Na+/Cl- Reuptake transporters found on Neuron 1.


At the synapse, serotonin binds to the serotonin receptors on Neuron 2 and sodium ions (Na+) enter Neuron 2.


a) What determines the concentration of serotonin in the synapse at any given time?


b) In the brains of people with depression, some neurons fire fewer action potentials in response to stimuli. Scientists have proposed that some symptoms of depression are caused by a deficiency of serotonin in regions of the brain.


One drug to treat depression is Prozac.  Prozac, a Selective Serotonin Reuptake Inhibitor (SSRI), blocks the action of the Serotonin/Na+/Cl- Reuptake transporter and increases the concentration of serotonin in the synapse.

How does Prozac minimize some of the symptoms of depression? In your explanation, address the post-synaptic potential and the probability of an action potential in Neuron 2.



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This material is based upon work supported by the National Science Foundation (DUE grants: 1438739, 1323162, 1347740, 0736952 and 1022653). Any opinions, findings and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the NSF.