Selective Serotonin Reuptake Inhibitors (SSRI) is a class of antidepressants that act within the brain to increase the amount of serotonin, a chemical nerves use to send messages to one another (neurotransmitter). Neurotransmitters are released by one nerve and taken up by other nerves. Those that are not taken up by other nerves are taken up by the same nerve that released them, a process called reuptake. By inhibiting reuptake, SSRIs allow more serotonin to be taken up by other nerves.
Definition