Scientists made a ‘zinc trap’ to prevent noise-induced hearing loss (in mice)


The music at a blaring concert, the din of tools on a construction site, or the firing of weapons can all cause noise-induced hearing loss. Acute traumatic injury to the ear from loud sounds can even progress to more serious conditions, including tinnitus and hyperacusis. People with tinnitus hear ringing or buzzing sounds that aren't there, while those with tinnitus hyperacusis usually experience normal sound levels as painful.

“Noise-induced hearing loss is very common and debilitating. It is a major cause of hearing loss, and one in five people worldwide suffer from it,” University of Pittsburgh otolaryngologist. Thanos Tzounopoulostell PopSci. “Hearing loss, especially noise-induced hearing loss, is very common, but its biological mechanism is not fully understood. »

[Related: It’s never too early to start protecting your hearing.]

Tzounopoulos is co-author of a new study that focuses on this type of hearing loss. Her research has uncovered the molecular mechanisms of noise-induced hearing loss in mice and shown that drugs can be used to alleviate it. The results are described in a study published on February 12 in the journal Proceedings of the National Academy of Sciences (PNAS).

What is the connection between zinc and hearing loss?

Zinc is an essential nutrient for living beings. It helps the immune system, metabolism function, senses of taste and smell, and even helps heal wounds.

About 90 percent Some of the zinc in the human body is bound to proteins to help them maintain their structure and function, while the remaining 10% is considered “free zinc.” It is not bound to proteins and is stored in tiny vesicles inside cells and dysregulation of zinc can cause problems at the cellular level.

“As previous literature has shown, dysregulation of zinc signaling can cause degeneration and cell death and contribute to conditions such as ischemia and degeneration of the optic nerve,” says Tzounopoulos.

A zinc trap

In the study, the team used mice to determine whether zinc dysregulation played a role in the damage that loud noises can cause to the inner ear. Just a few hours after the mice were exposed to loud sounds, a strong release of zinc into the space between cells occurred. This extra zinc eventually damaged the cells and disrupted normal communication between them.

[Related: Why what we see influences what we hear.]

The team then administered a slow-release compound that trapped excess free zinc in two ways: through a mouse's inner ear or through the abdomen. Mice treated with this compound were less prone to hearing loss and protected from noise-induced damage.

“The fact that both options were effective in protecting mice from hearing loss suggests that, in the future, we could develop a pill that a person could take before a known exposure to loud noise to protect against hearing loss. hearing,” says Tzounopoulos. “We might be able to attenuate hearing loss after noise exposure or even prevent hearing loss if it was administered in anticipation of noise exposure.”

How to prevent hearing loss

The team is currently developing a treatment for preclinical safety studies with the eventual goal of making it an over-the-counter option to protect against hearing loss. According to Tzounopoulos' research, only 100 decibels– the sound of an average football game or lawn mower – is enough to trigger the rapid release of zinc that damages the inner ear and causes hearing problems.

“Prevention is the best way to protect against hearing loss,” says Tzounopoulos. “Always wear earplugs when going to a loud concert or expecting to be in a noisy environment.”

Other choice include turning down the music in headphones, limiting excessive noise exposure, and moving away from noises as much as possible.



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