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Credit: CC0 Public Domain
Credit: CC0 Public Domain
Anyone who has ever been to a loud concert knows the feeling of ringing in the ears. Some people experience temporary or even permanent hearing loss or drastic changes in their perception of sound after the loud noises stop. Thanos Tzounopoulos, Ph.D., director of the Pittsburgh Hearing Research Center at the University of Pittsburgh School of Medicine, has focused his scientific career on investigating how hearing works and developing ways to treat tinnitus. and hearing loss.
In a paper published in Proceedings of the National Academy of Sciences, Tzounopoulos and his colleagues at Pitt, Amantha Thathiah, Ph.D., and Chris Cunningham, Ph.D., have discovered a molecular mechanism of noise-induced hearing loss and show that it can be alleviated with drugs.
The study showed that noise-induced hearing loss, which affects millions of Americans, stems from cellular damage in the inner ear that is linked to excess free-floating zinc—a mineral that is essential for proper cellular function and hearing. Experiments in mice showed that drugs that act as molecular sponges that trap excess zinc can help restore lost hearing or, if administered before an expected loud sound exposure, can protect against hearing loss.
“Noise-induced hearing loss affects millions of lives, but, because the biology of hearing loss is not fully understood, preventing hearing loss has been an ongoing challenge,” said senior author Thanos Tzounopoulos, Ph.D. ., professor and vice president. of otolaryngology research at Pitt.
While some experience noise-induced hearing loss as a result of an acute traumatic ear injury, others notice a sudden hearing loss after being repeatedly exposed to loud noise, for example on a battlefield or on a construction site. Others notice that their hearing worsens after attending a loud musical performance.
Researchers say such noise-induced hearing loss can be debilitating. Some people start hearing sounds that aren’t there, developing a condition called tinnitus, which severely affects a person’s quality of life.
Tzounopoulos’ research, which focuses on the biology of hearing, tinnitus and hearing loss, sought to determine the mechanistic underpinnings of the condition in an effort to lay the groundwork for the development of effective and minimally invasive treatments in the future.
By conducting experiments on mice and isolated cells of the inner ear, the researchers found that a few hours after the mice were exposed to loud noise, the level of zinc in their inner ear increased. Loud exposure causes a powerful release of zinc into the extracellular and intracellular space, which ultimately leads to cellular damage and disrupts normal cell-to-cell communication.
Fortunately, this discovery opens the door to a possible solution. Experiments showed that mice that were treated with a slow-release compound that blocked excess free zinc were less prone to hearing loss and were protected from noise-induced damage.
Researchers are currently developing a treatment that will be tested in preclinical safety studies with the goal of making it available as a simple, over-the-counter option to protect yourself from hearing loss.
Other study authors are first author Brandon Bizup, Ph.D., and co-author Sofie Brutsaert, both of Pitt.
Disruption of cochlear zinc signaling is associated with noise-induced hearing loss and zinc chelation enhances cochlear recovery, Proceedings of the National Academy of Sciences (2024). DOI: 10.1073/pnas.2310561121
Proceedings of the National Academy of Sciences