reuptake

When a nerve cell sends a signal, it releases a neurotransmitter into the synapse, the gap separating it from the next cell. The message does not last long. Proteins called transporters sit in the membrane of the releasing cell and draw the neurotransmitter back inside, which limits or shuts off the signal. The US National Institute on Drug Abuse describes these transporters as recycling neurotransmitters, bringing them back into the neuron that released them. That recovery step is reuptake.

Because reuptake is what ends the message, interfering with it is one of the most direct ways a drug can change brain signalling. A reuptake inhibitor binds to the transporter and stops it doing its job, so the neurotransmitter stays in the gap for longer and keeps acting on the receiving cell. Nothing new is added to the brain; what changes is how long the cell's own chemistry stays available.

A large share of psychiatric medicine works this way, and the naming usually says which messengers are involved. A serotonin reuptake inhibitor acts on serotonin transporters. A norepinephrine, dopamine and serotonin reuptake inhibitor acts on all three. Which transporters a drug blocks, and how strongly, is a large part of what separates one medicine in this family from another.