Anxiety Linked to Brain Chemical

§ May 14th, 2009 § Filed under brain research, depression, neuroscience, plasticity § No Comments

Scientists have linked low levels of a particular brain growth factor (fibroblast growth factor 2) to a disposition toward anxiety.  The University of Michigan study on rats appears in the May 13 issue of The Journal of Neuroscience. Since FGF2 increases the survival rate of new brain cells, the findings also highlight the role of neurogenesis, or cell birth and integration in the adult brain, in reducing anxiety. These findings may offer new possibilities for the treatment of anxiety and potentially depression.

Previous human studies led by the senior author, Huda Akil, PhD, at the University of Michigan and team at the Pritzker Consortium, showed that people with severe depression had low levels of FGF2, but couldn’t say whether low FGF2 levels caused the disease or were caused by it.

Javier Perez, PhD, also at the University of Michigan, bred rats for high or low anxiety for over 19 generations. The researchers found lower FGF2 levels in rats bred for high anxiety compared to those bred for low anxiety.

The study also found that providing a more stimulating and interesting environment for the rats increased FGF2 levels and reduced anxiety.  They also found that FGF2 treatment alone reduced anxiety behaviors in the high-anxiety rats.

“We have discovered that FGF2 has two important new roles: it’s a genetic vulnerability factor for anxiety and a mediator for how the environment affects different individuals. This is surprising, as FGF2 and related molecules are known primarily for organizing the brain during development and repairing it after injury,” Perez said.

The findings further indicate that FGF2 may in part reduce anxiety because it increases the survival of new cells in the hippocampus. Previous research has suggested that depression decreases the production and incorporation of new brain cells (neurogenesis). High-anxiety rats produced the same number of new brain cells as low-anxiety rats, but more of these new cells died off. FGF2 treatment and environmental enrichment each restored brain cell survival.

“This discovery may pave the way for new, more specific treatments for anxiety that will not be based on sedation — like currently prescribed drugs — but will instead fight the real cause of the disease,” said Pier Vincenzo Piazza, MD, PhD, Director of the Neurocentre Magendie an INSERM/University of Bordeaux institution in France, an expert on the role of neurogenesis in addiction and anxiety (not involved in the current study).

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