This is straight out of my college Anatomy book:
"The management of clinical depression is one example of how contemporary pyschopharmacology has supplemented counseling approaches. Some cases of depression result from deficienies of the monoamine neurotransmitters. Thus, they yield to the drugs that prolong the effects of the monoamines already present at the synapses. One of the the earliest discovered antidepressants was imipramine, which blocks the synaptic reuptake of serotonin and norepinephrine. However, it produces undesirable side effects such as dry mouth and irregular cardiac rhythms; it has been largely replaced by Prozac (fluoxetine). which blockss serotonin reuptake and prolongs its mood elevating effects; thus it is called a selective serotonin reuptake inhibitor (SSRI). Prozac is also used to treat fear of rejection, excess sensitivity to criticism, lack of self-esteem, and inability to experience pleasure, all of which were long handled only though counseling, group therapy, and psychoanalysis. After monoamines are taken up from the synapse, they are degraded by monoamine oxidase (MAO). Drugs called MAO inhibitors interfere with the breakdown of monoamine neurotransmitters and provide another pharmacological approach to depression"

Take what you want from this, but Im pretty sure my text book isnt gonna to propagate propaganda.