Depression caused by a lack of P11 Protein

January 5th, 2006

Serotonin

Nobel Laureate researchers discovered a protein called P11, which they believe acts like an antidepressant.

First reported in Science, Paul Greengard, Ph.D, a Rockefeller University neuroscientist who also received the 2000 Nobel Prize in Physiology or Medicine said, "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."

Greengard and his colleagues discovered that P11 protein is able to help in the regulation of serotonin. Low levels of serotonin have long been known to cause depression and anxiety.

Serotonin selective re-uptake inhibitors (SSRIs) are a commonly prescribed medication help compensate for the loss of serotonin signaling and boost the levels and binding ability for serotonin to the brain’s receptors.

The researchers looked into what proteins worked with these receptors. They discovered that 5-HT1B interacts with P11 protein. The P11 is and aid to the receptors by making the cells work better at attracting the serotonin. The scientists felt that lowered P11 levels would create depression and anxiety.

The study involved mice and non-depressed humans. They measured the levels of P11 protein and found that it was lower in depressed humans and helpless mice. The researchers further studied the P11 levels when the mice were subjected to antidepressant medications and therapy – a tricyclic, a monoamine oxidase (MAO) inhibitor, and electroconvulsive therapy (ECT).

"These three different ways of treating depression all caused an increase in the amount of p11 in the brains of these mice," said Greengard. "They all work in totally different ways, but in all cases they caused the same biochemical change. So, it's pretty convincing that p11 is associated with the main therapeutic action of antidepressant drugs."

Further research will be conducted into why the antidepressant medications increase the P11 levels. In understanding the way the P11 protein works, research may offer other solutions for depression and anxiety in the future.