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Fun With Serotonin

Serotonin levels affect physical illness, as well as mood? The
neurotransmitter shows promise as cancer killer.

Serotonin, a neurotransmitter that affects mood, appetite and libido, has been shown to kill one type of cancer cell, fueling hope for new drug therapies as well as concern that popular antidepressants interfere with serotonin's cancer-fighting properties.

In test-tube experiments, scientists studied the effect of serotonin on Burkitt's lymphoma, a cancer of the immune system. In high concentrations, serotonin, which is found in the brain, gut and blood platelets, entered cancer cells and caused them to self-destruct.

"If we can mimic serotonin's action, we might be able to halt Burkitt's lymphoma," says Randy Blakely, Ph.D., director of Vanderbilt University's Center for Molecular Neuroscience in Tennessee, and co-author of the study, which appeared in the medical journal Blood.

Scientists chose Burkitt's lymphoma because it has relatively few survival genes, making it easier to trick the cells into self-destructing, according to co-author John Gordon, Ph.D., a professor of cellular immunology at the University of Birmingham in England.

The disease-fighting properties of serotonin suggest a possible link between disposition and cancer, an illness some patients hope to defeat with positive thinking. There is no empirical proof of the mind's curative power, but "mood could effect the immune system and therefore the development of cancer," maintains Gordon.

When Gordon and Blakely first reported their findings this spring, one corollary sparked panic: Selective serotonin reuptake inhibitors (SSRIs), the antidepressants of choice in contemporary pharmacotherapy, prevent serotonin from entering Burkitt's lymphoma cells. The British press widely misinterpreted this finding as evidence that the three SSRIs studied, Prozac, Paxil and Celexa, may increase the risk of cancer.

"Fifty million people worldwide take SSRIs," says Gordon. "There is no evidence of any link between SSRIs and cancer."