All you need to know about Prozac

Dependence of mood on number of neurotransmitters Serotonin and Norepinephrine

Pharmacologic agents that inhibit 5HT uptake are generally considered antidepressants. An additional finding is that the antimanic agent, lithium, increases tryptophan availability. This suggests that serotonin functioning may be impaired in both mania and depression. A growing appreciation of the interactions of various neurotransmitters has resulted in a theory known as the permissive hypothesis.

The SSRIs mode of functioning

This theory explains a variety of findings such as the fact that lithium is effective in both the mania and the depressed phases of the bipolar disorder. This theory suggests that serotonin has a key role in determining whether changes in norepinephrine result in psychopathology. Simply put low serotonin permits the altered norepinephrine to ‘act’. If serotonin functioning and norepinephrine functioning are both low then the behavior is depressive. If serotonin is low and the norepinephrine is high the behavior is manic.