Prozak (fluoxetine) is among the Selective Serotonin Reuptake Inhibitors (SSRIs), aka. second-generation antidepressants. As all SSRIs, Prozak blocks the reuptake transporter for serotonin, preventing it from being taken back to the axon terminal. Since this transporter is blocked, serotonin remains in the synaptic cleft for long periods, continuing to have its effect on the postsynaptic neuron. Although this effect takes place very quickly, depression symptoms take long periods to be alleviated. This phenomenon is not fully understood, but it is interesting to note that Prozak increases the production of new neurons in the hippocampus – a limbic structure that is very vulnerable to stress-induced damage. Therefore, it is suspected that this renewal in the hippocampus is exactly the reason behind this antidepressant’s effect.