Northwestern Medicine scientists have discovered a pathway in the brain that could be used to develop new methods for easing depression, a study published Tuesday shows.

The discovery could lead to the development of a new antidepressant more effective for people who do not get sufficient relief from current drugs, according to a news release. Between 10 and 20 percent of the population experience major depressive disorder at some point in their lives.

“The biochemical changes in the brain that lead to depression are not well understood, and many patients fail to respond to currently available drugs,” Feinberg Prof. Jack Kessler, a Northwestern Medicine neurologist, said in the news release. “Our findings may not only help to understand the causes of depression, but also may provide a new biochemical target for developing more effective therapies.”

The breakthrough was part of a study published in Molecular Psychiatry, a scientific journal.

Scientists observed for the first time during the study that antidepressants such as Prozac and tricyclics target part of the hippocampus –– the center of emotion, memory and the autonomic nervous system –– called the BMP signaling pathway. A signaling pathway is a group of molecules that work together to control one or more cell functions.

Prozac and tricyclics blocked the BMP signaling pathway and prompted the brain to trigger more neurons, according to the release. These neurons are associated with memory and mood functions.

After determining the pathway’s importance, Noggin –– a brain protein known for blocking the BMP pathway –– was administered to depressed mice. The protein stimulated new neurons and had a strong antidepressant effect on the mice.

Mice with Noggin were more energetic when put in depression- or anxiety-causing situations, such as being held upside down by their tails, according to the release.

The study was funded by the National Institute of Neurological Disorders and Strokes, the National Institutes of Health and the Davee Foundation.

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