What is the action of Prozac in the central nervous system?

Prozac is an SSRI (selective serotonin reuptake inhibitor) & acts to keep serotonin in the synapse (space between neurons). This is accomplished by inhibiting the normal process of extracting serotonin from the synapse by a process called reuptake. Keeping serotonin in the synapse longer causes the serotonergic neruons to be more effective.