Discovery

A single protein in the brain seems to exert significant influence over feelings of despair, according to a new study in mice. Previous work has suggested that genetic mutations can predispose people to certain psychological disorders, such as depression.

Rodents engineered to have higher levels of the protein coped better with the frustrating challenges presented to them in the experiment. Researchers speculate that the protein – called delta-FosB – might also help the human brain handle stressful situations better. Delta-FosB functions as a “transcription factor”, meaning that it boosts production of other molecules inside cells. Working in the lab of Eric Nestler, Berton’s team showed that delta-FosB specifically increases the production of a compound called “substance P”.

Earlier experiments suggested that substance P can alter pain sensitivity, but Berton emphasises that all the groups of mice in his study had the same reaction to various painful stimuli when he tested this specifically. He adds that substance P, a peptide molecule, is known to increase feelings of anxiety in people.

The experiments exposed mice to a test involving mild but painful electric shocks from a wire mesh at the bottom of a cage. The scientists observed how hard each mouse worked to avoid the shocks. Next, researchers created mice that overproduce delta-FosB, by injecting a harmless virus loaded with extra copies of the genetic code for delta-FosB into the animals’ brains.

Scientists believes the animals with more delta-FosB simply coped better with the stress created by repeated exposure to the electric shocks in a situation from which there was no escape.

Journal reference: Neuron (DOI: 10.1016/j.neuron.2007.06.033)

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