If you've been to a loud concert, you may have experienced the aftereffects, which might have included ringing in the ears. Many people experience hearing loss for a variety of reasons. Our hearing declines as we age, but loud noises - whether they are sustained such as those in a loud concerts, or are short bursts like fireworks - can also cause hearing damage. There are also injuries, illnesses, and medications that can cause hearing loss. Researchers have now learned more about how ears are damaged by loud noises, and how that loss can be reversed. The findings have been reported in the Proceedings of the National Academy of Sciences (PNAS).
Millions of people are affected by noise-induced hearing loss, which is associated with damage to cells in the inner ear. Free-floating zinc is crucial to the function of those cells and the transmission of sounds, and that system becomes disrupted when noise damages the ears.
Using a mouse model, researchers have determined that after exposure to loud noises, the zinc levels in the inner ears of those noise-exposed mice spiked dramatically. Loud sounds appear to release a significant amount of zinc into the spaces in and between cells in the inner ear. Those zinc dumps can eventually cause damage, and interfere with communication between the cells in the area.
However, the researchers wondered if there was a way to mitigate the damage caused by the sudden release of a large amount of zinc. They showed that certain drugs can trap the excess zinc like a sponge, which seems to relieve hearing loss once it has happened. These drugs may also prevent hearing loss if they are administered before exposure to loud noises. Mice that were treated with a compound that released slowly were less likely to experience hearing loss or ear damage after noise exposure.
"Noise-induced hearing loss impairs millions of lives but, because the biology of hearing loss is not fully understood, preventing hearing loss has been an ongoing challenge," said senior study author Thanos Tzounopoulos, PhD, the director of the Pittsburgh Hearing Research Center at the University of Pittsburgh School of Medicine, among other appointments.
Now the investigators are working on a treatment that can be used in pre-clinical testing. The ultimate aim is to create an over-the-counter medication that can prevent hearing loss.
Sources: University of Pittsburgh, Proceedings of the National Academy of Sciences (PNAS)
