Growing Up to Prozac: Drug makes new neurons mature faster

Peter Pan won't be pleased to hear the latest theory about how Prozac works. A new study shows that the antidepressant stimulates growth of neurons in the hippocampus and speeds the young brain cells toward maturity. The maturation process could be the mechanism by which the drug relieves depression.

Fluoxetine, the drug commonly known as Prozac, has been used to treat depression since the 1980s. Prozac and other SSRIs (selective serotonin reuptake inhibitors) block the ability of the neurons to take up serotonin, thereby raising levels of the active neurotransmitter in the brain. When people with depression begin taking such drugs, serotonin levels in the brain increase rapidly, but it often takes 2 to 4 weeks before they begin to feel better.

The new study, published Feb. 6 in the Journal of Neuroscience, suggests that the lag is due to the time it takes for serotonin to stimulate new neurons to grow, mature, and integrate into brain circuits.

René Hen, a neuroscientist at Columbia University, and his colleagues tested the long-term effects of Prozac treatment on a specially bred strain of nervous mice.

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