BODY WATCH : Nervousness May Be a Gene Thing

What makes mice nervous, besides hungry cats?

Their genes, it seems. And the genetic contribution to mouse mood could help researchers understand the biological component of human anxiety.

Dr. Jonathan Flint, a psychiatrist at Oxford’s John Radcliffe Hospital and colleagues report in the Sept. 8 issue of Science that they have located three genetic regions on the chromosomes of mice that appear to govern “emotionality,” a trait much studied in rodents. Rats with high emotionality show great anxiety in unfamiliar or frightening situations.

Flint put more than 800 mice through mazes designed to be “potentially frightening” environments, with some open, brightly illuminated areas. Some mice were unperturbed, but others were so upset that they froze in their tracks and defecated.

Comparing the genes of the 86 mice most bothered by mazes with those of the 86 most sanguine mice revealed three common chromosomal regions that the researchers believe contribute to the behavior.

Flint cautioned that nurture still dominates nature. The genetic component probably accounts for just 20% of variability seen in the mice. “The environmental determinant is by far the greater,” Flint says.