As anyone who has ever had a limb in a cast knows, muscles lose mass and strength rapidly when they are not used. This process, known as muscle disuse atrophy, may be prevented by a drug recently tested in mice by researchers supported by the National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS). Muscle atrophy occurs not only when a limb is immobilized, but also in connection with certain diseases, nerve damage, weightlessness, and age-related inactivity.

H. Lee Sweeney, Ph.D., and his colleagues at the Pennsylvania Muscle Institute and the University of Pennsylvania Medical School tested a protease inhibitor called Bowman-Birk Inhibitor Concentrate (BBIC) to see if it would prevent muscle atrophy in mice. Proteases are enzymes that break down proteins in muscles that are diseased or unused. Dr. Sweeney's lab tested BBIC to see if it would stop this process and prevent the muscle loss.

For the experiment, mice were suspended by their tails for two weeks so that they were free to move around, but using only their front legs. They were fed a diet with BBIC included or an inactive form of the supplement. Some mice were also treated with BBIC, but were not elevated, and were free to move around normally. Suspended mice treated with BBIC retained muscle mass, muscle fiber size, and strength significantly better than the control mice. There were no adverse effects from BBIC, and it did not cause hypertrophy (overgrowth) of muscle in non-suspended mice that were fed the supplement.

According to the researchers, effective methods for preventing muscle atrophy could significantly reduce the burden of many diseases and disorders. Preventing atrophy could improve a patient's overall recovery from injuries, as well as enhancing the quality of life for patients with various diseases, including the muscular dystrophies, reducing their dependence on caregivers.

The mission of the National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS), a part of the Department of Health and Human Services' National Institutes of Health, is to support research into the causes, treatment, and prevention of arthritis and musculoskeletal and skin diseases; the training of basic and clinical scientists to carry out this research; and the dissemination of information on research progress in these diseases. For more information about NIAMS, call the information clearinghouse at (301) 495-4484 or (877) 22-NIAMS (free call) or visit the NIAMS Web site at http://www.niams.nih.gov.

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Morris C, et. al. Attenuation of skeletal muscle atrophy via protease inhibition. J Appl Physiol 2005;99:1719-1727.