Depression Support Journal

(The New York Times News Service) -- Researchers have identified a protein that seems to play a key role in fighting depression.

The protein, called p11, appears to help regulate signaling of the brain chemical serotonin. A target of the antidepressants called selective serotonin reuptake inhibitors, which include Prozac, serotonin has been linked to depression and anxiety disorders, the study notes.

"Mice deficient in this protein, called p11, display depression-like behaviors, while those with sufficient amounts behave as if they have been treated with antidepressants," study author Paul Greengard, a Nobel Prize-winning neuroscientist at Rockefeller University in New York City, says in a prepared statement.

The experiments with mice revealed how p11 works with the serotonin receptor 5-HT1B, which has also been associated with obsessive-compulsive disorder, drug addiction, anxiety and aggression, as well as depression.

The findings appear in the Jan. 6 issue of Science.

"P11 can be viewed as a protein that links the pathophysiology of depression with the serotonin system," says lead study author Per Svenningsson, from the department of physiology and pharmacology at the Karolinska Institute, in Stockholm, Sweden.

Depression is often treated with compounds such as serotonin reuptake inhibitors, which increase levels of serotonin. "The released serotonin acts on 14 serotonin receptors, some of which mediate therapeutic actions and some of which mediate side effects," he adds.

The researchers studied one specific serotonin receptor, the 5-HT1B receptor, and found that it interacts with p11. The protein is depleted in tissue in so-called "helpless" mice, which exhibit behaviors similar to depressed humans. It's also depleted in the brain tissue of depressed patients, the researchers says.

"Mice that over-express p11 are hyperactive, and act as if they are on antidepressant medication," Svenningsson says. Conversely, mice that have no p11 "act as they are somewhat depressed and show less responsivity toward antidepressant medications," he adds.

While there's no immediate clinical application for this finding, Svenningsson says "this study emphasizes that the 5-HT1B receptor, with its interaction with p11, may be linked to depression. It may turn out that future antidepressants could target this receptor, andprobably some additional 5-HT receptors, but not necessarily all 5-HT receptors. Hopefully, such antidepressants will have fewer side effects."

One expert agrees that p11 might become a target for antidepressants in the future.

"Whilst p11 is a potential source of new therapies, unfortunately at the moment we do not know enough about p11 to target it selectively with drugs," says Trevor Sharp, a reader in pharmacology at the University of Oxford, Great Britain, and author of an accompanying perspective article in the journal.

"However, p11 is functionally linked to a serotonin receptor, and there are a number of drugs in development that act selectively on this receptor, and some of these drugs show antidepressant potential in laboratory models," Sharp says. "We will know in a few years whether these kinds of drugs are better than the antidepressant treatments that we already have."

Copyright 2006 The New York Times News Service. All rights reserved.

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• #2 Comment from healthunter2
  1/6/07 6:00 PM | Permalink

  Actualy, you can get L-Tryptophan in the United States.  The sale of L-Tryptophan was never banned in the US.  They banned the imports.  They yanked everything off the shelves because of the contamination issue.  Amazing how they never lifted that ban though, and since 99 percent of the manufacturing capacity was oversea's, that effectively killed L-Tryptophan.  However, its sale in the US has never been banned.  Its been made in increasingly larger quantities in the US ever since.  Look up L-Tryptophan sales on the Net and you will see a myriad of online Pharmacies selling it.  Some want a precription for it and some don't.  Its over the counter sales though, so the ones that want a precription in the US are either wrong or covering their butt.
• #1 Comment from homelessoldwoman
  1/14/06 4:24 PM | Permalink

  I wonder if this has anything to do with tryptophan? I've noticed that we still can't get encapsulated triptophan, yet Imitrex, which is for migraines is sumatripton which sounds like a made made triptophan. I just cook two turkeys and mix meat and gravy and have that, which I freeze in small baggies for six months, on rice twice a week and I seem to do better. I take a good brand of SAMe. also, which my pharmacist turned me onto. Sometimes, even in this enlightened day and age you can't get a pure dosage of it. It helps to even out mood swings and takes away the physical aches and pains of depression. Champion Nutrition makes a product JSF that helps your body manufacture SAMe and has turmeric/curcumin in it.