Laid-Back Mice Provide Anxiety Clues
May Lead to New Treatments for Anxiety Disorders
Oct. 2, 2002 -- Some mice just naturally seem to deal with stress and anxiety better than others, and researchers say humans may soon benefit from this genetic quirk.
A new study shows mice that lack a certain enzyme are much more sensitive to their own calming brain chemicals. And the authors suggest that targeting this enzyme might eventually provide a new way to treat the 20 million Americans who suffer from chronic anxiety.
An estimated one in four people in the U.S. will suffer from excessive anxiety at some point in their lives. Although prescription anxiety-reducing drugs can relieve the physical symptoms, such as increased heart rate, shortness of breath, sweating, trembling, and fatigue, long-term use of the drugs is discouraged because they can be addictive and cause sedation.
In the study, Robert Messing, MD, and colleagues at the Gallo Clinic and Research Center at the University of California, San Francisco, found that certain mice lack the gene that makes an enzyme called protein kinase C (PKCe). These mice were also less likely to exhibit anxious behaviors and had lower levels of stress hormones.
Researchers say the absence of this gene may work in the mice's favor -- reducing anxiety by making them more sensitive to the brain's own calming substances, called neurosteroids.
Earlier studies have also shown mice that lack the PKCe gene are more sensitive to other substances that affect brain activity, including alcohol and barbiturates.
As researchers learn more about exactly how PKCe works within the brain, the researchers say drugs may be developed that inhibit this enzyme and mimic the effects of the genetic mutation found in the relaxed mice -- without the addictive and sedating side effects of current treatments.
The study appears in the Oct. 1 issue of the Journal of Clinical Investigation.