"Loss of balance is a significant problem in the elderly because it can lead to dangerous falls and injuries," says one of the study's principal investigators, David M. Ornitz, M.D., Ph.D., professor of molecular biology and pharmacology at the School of Medicine. "Loss of balance also is a problem for astronauts following exposure to zero gravity. Now that we've discovered this new gene, we can begin to understand the mechanisms that allow the body to sense gravity and maintain balance."
Balance is determined and regulated by the vestibular system, which is housed in the inner ear. To detect gravity, a cluster of particles called otoconia rests atop hair cells lining the inner ear. Like a water buoy guided by the movement of waves, otoconia are displaced as the body moves. As otoconia move, they shift the hair cells, which triggers the cells to send messages to the brain.
Studies suggest that otoconia are only produced during development, and that they progressively degrade throughout life. Scientists believe otoconia become eroded during normal aging, which can lead to balance disorders. But little is understood about how otoconia develop, and whether it may be possible to stimulate the production or regeneration of these particles.
Ornitz's team genetically analyzed two strains of mice tilted (tlt) and mergulhador (mlh) known to have problems with balance. These mice walk with their heads tilted and have trouble orienting themselves in water but have no hearing problems. Moreover, they are missing their otoconia but have normal sensory hair cells. The team discovered that the two strains both have a mutation in the sam
Contact: Gila Z. Reckess
Washington University School of Medicine