Serotonin is a neurotransmitter present in the brain, small intestines, platelets, etc. It is said to involve in emotional control such as lifting
and suppression as well as sleep and wake, and dieting. Insufficiency of serotonin in the brain is considered as one of the causes for depression.
Selective serotonin reuptake inhibitors (SSRIs) bind to serotonin transporters, thereby inhibits serotonin reuptake in the brain resulting in an increase
in the serotonin concentration in the synaptic gaps. SSRIs are under investigation as antidepressants.