US researchers have discovered the role of zinc — a mineral that is essential for proper cellular function and hearing — in noise-induced hearing loss and showed that it could be mitigated with medication.
Besides the feeling of ringing ears, some people experience temporary or even permanent hearing loss or drastic changes in their perception of sound after being exposed to loud noises.
The team from the University of Pittsburgh showed that noise-induced hearing loss, which affects millions of people globally, stems from cellular damage in the inner ear that is associated with the excess of free-floating zinc.
Experiments in mice showed drugs that work as molecular sponges trapping excess zinc can help restore lost hearing or, if administered before an expected loud sound exposure, can protect from hearing loss.
“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 Thanos Tzounopoulos, Professor and vice-chair of research of otolaryngology at the varsity.
By performing experiments in mice and on isolated cells of the inner ear, researchers found that hours after mice are exposed to loud noise, their inner ear zinc level spikes. Loud sound exposure causes a robust release of zinc into the extra and intracellular space which, ultimately, leads to cellular damage and disrupts normal cell to cell communication.
This discovery, published in the Proceedings of the National Academy of Sciences, opens doors for a possible solution. Experiments showed mice who were treated with a slow-releasing compound that trapped excess free zinc were less prone to hearing loss and were protected from noise-induced damage.
Researchers are currently developing a treatment to be tested in preclinical safety studies with the goal of making it available as a simple, over-the-counter option to protect oneself from hearing loss.
