50 years ago, an experimental drug hinted at serotonin’s many roles in the brain

 Excerpt from the October 3, 1970 issue of Science News

the libido-boosting drug Addyi

: Fifty years ago, scientists were just starting to figure out serotonin’s role in the brain. Today, treatments for depression and low sex drive (the libido-boosting drug Addyi is shown) target the chemical messenger.

Sprout Pharmaceuticals

Science News, October 3, 1970

Clues from a chemical  Science News, October 3, 1970

An experimental drug’s effects on the sexual behavior of certain animals is arousing interest among investigators.… The drug, para-chlorophenylalanine … reduces the level of a naturally occurring neurochemical, serotonin, in the brain of rats, mice and dogs.… Little is known about how serotonin acts in the brain, and investigators quickly recognized that PCPA could be used to study this brain chemical.


PCPA helped e­stablish serotonin’s role in regulating sexual desire, as well as sleep, appetite and mood. The chemical messenger has become key to one common class of antidepressant drugs called selective serotonin r­euptake inhibitors. Identified in 1974, SSRIs work by increasing the brain’s serotonin levels. But such drugs can hinder sexual desire. One SSRI that failed to relieve depression in humans found a second life as a treatment for sexual dysfunction. Approved by the U.S. Food and Drug Administration in 2015, this “little pink pill,” sold as Addyi, may boost sex drive in women by lowering serotonin in the brain’s reward centers.

Lisa Grossman is the astronomy writer. She has a degree in astronomy from Cornell University and a graduate certificate in science writing from University of California, Santa Cruz. She lives near Boston.

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