Maybe you know the feeling: you’ve just been to a concert and afterwards your ears are still ringing. Scientists have now discovered how loud noise can ultimately lead to hearing damage – and also how you can largely prevent this.
It is a happy day for people who like loud music: it looks like a medicine will come onto the market in the near future that can largely counteract hearing damage. American scientists have discovered that the hair cells (see box) in the inner ear do not simply fall over, but that this is often preceded by a step. For example, exposure to loud noises can lead to an overabundance of zinc in the inner ear, which can damage the hair cells, ultimately damaging them. Scientist Thanos Tzounopoulos contributed to the study. He tells Scientias.nl: “People often don’t realize how harmful loud noises can be. Our research shows that 100 decibels is enough to cause an overabundance of zinc in the inner ear, which can damage it.” The research has been published in the journal Proceedings of the National Academy of Sciences.
Hair cells
Hair cells are located in the ear and convert sound waves into signals that are transmitted to our brain via nerves. In fact, these hair cells ensure that you can hear (well). But unfortunately they are not untouchable: they can be damaged by loud noises, such as extremely loud music. This can then lead to hearing loss and tinnitus. And that is in principle permanent; there is currently no way to repair the hair cells.
Zinc in the ear
The new research first of all offers a surprising answer to the question of how exactly hearing loss occurs and therefore points to the development of an abundance of zinc. But what is zinc’s purpose in the inner ear? Tzounopoulos explains: “Zinc is an essential element needed to make life possible. The human body itself uses zinc. Of this, 90% is bound to proteins, where its main task is to support structure and function. The remaining 10% of the zinc is therefore ‘free’ and not bound to proteins. The free zinc is stored in vesicles that are located in the cells themselves. This zinc is used in the brain and inner ear to promote communication between cells and to process stimuli.” However, problems arise when these cells have to process too many and too strong stimuli. This can cause an excess of zinc, which can then damage the hair cells.
Mice
Tzounopoulos’ team used mice for the research. First, the team isolated certain parts of the ear in preparation. These mice were then exposed to loud noise. Due to the insulation, not all cells in the ear were affected by the noise, but only specific cells. Afterwards, the research team examined these cells. This showed that, even after many hours had passed, the cells without insulation had much higher zinc levels than the cells that were protected.
Tinnitus
The results of the research are very promising. Tzounopoulos’ team has made one last but very important discovery. “The most important discovery is that we can capture this excess zinc,” Tzounopoulos explains. “We can do this by using a ‘zinc chelator’, which essentially acts like a sponge.” Experiments reveal that mice in which excess zinc in the ear was captured by such a ‘zinc sponge’ were less susceptible to hearing loss and were better protected against noise-induced damage to the hair cells. The scientist’s ultimate goal is to develop a drug that makes this ‘zinc sponge’ available to people in a safe way. The scientist is hopeful that tinnitus can at least be better prevented in this way.
However, Tzounopoulos’ team is far from done. “The next step in our research is to figure out why the body responds with such a large amount of zinc,” concludes Tzounopoulos. “We are also trying to better understand how exactly zinc can damage the cells in the inner ear. For the time being, I still advise people to always wear earplugs during a concert and in noisy environments.” Because Tzounopoulos also emphasizes that once damaged hair cells in the inner ear do not recover. So it is better to be careful – even with a miracle cure such as the (future) zinc sponge.
2024-02-18 18:03:19
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