Serotonin
(5-hydroxytryptamine, 5HT) plays an important role in many
behaviors including sleep, appetite, memory, sexual
behavior, neuroendocrine function, and mood. In the brain,
the highest level of serotonin is found in the dorsal and
median raphe nuclear complex. Once serotonin is released it
must be eliminated somehow to allow for further
signaling.
Serotonis is cleared from the synapse by a reuptake
pump that is powered by Na+ Cl-
and K+ ions.
Selective
serotonin reuptake inhibitors (SSRIs like Prozac) act
primarily at the 5HT transporter protein and have limited,
if any, reaction with other neurotransmitter systems. SSRIs
bind to the transporter protein directly and block the
reuptake process. Consequently, more serotonin remains in
the cleft where it is free to travel further to more distant
receptors as well as continue to react with nearby
receptors.
