A growing amount of scientists support the view that people with depression have an imbalance of the brain's neurotransmitters, the chemicals that allow nerve cells in the brain to communicate with each other. They believe that an imbalance in serotonin, one of these neurotransmitters, may be an important factor in the development and severity of depression. Abnormal serotonin functioning is theorized to cause psychological disorders such as depression, anxiety, irritability, abnormal appetite, and sleep disturbance. A group of drugs that target serotonin are called SSRIs or Selective Serotonin Reuptake Inhibitors. Some of the big names are Prozac, Zoloft, and Paxil. Because of their effect on serotonin, these drugs have been used not only in depression but also OCD, panic disorder, bulimia and anorexia, schizophrenia, alcoholism, borderline personality disorder, impulsive aggressive behavior, postpartum depression, PMS, social phobia, pedophilia, migraine headaches, and anxiety disorder (Appleton, 2000).
Even though they begin to alter brain chemistry with the first dose, these SSRI's take several weeks to be effective.
Research now suggests that antidepressant effects result from slow-onset adaptive changes within the brain cells. It also appears that activation of chemical messenger pathways within neurons and changes in the way that genes in brain cells are expressed, are the critical events in the long-term adaptations in neuronal function that is relevant to antidepressant drug action. (http://www.nimh.nih.gov/publicat/depresfact.cfm)
Fluoxetine (Prozac), is used to treat depression, obsessive-compulsive disorders, and some eating disorders. Many scientists believe that Prozac works by blocking the action of the serotonin uptake pump. When serotonin is released from the sending nerve cell some of it is reabsorbed by an uptake pump. By blocking the serotonin uptake pump, Prozac increases the amount of active serotonin that can be delivered to the receiving nerve cell. This may help message transmission return to normal (Sue,Sue,Sue,