Scientists discover a ‘chemical ear muff’ drug that can protect hearing without dampening all noise in an effort to prevent hearing problems from a quarter of American soldiers
- Between 16.4 and 26.6 percent of the American wars in Iraq and Afghanistan suffer from hearing loss or tinnitus
- Researchers from the University of Iowa and Washington University in St. Louis are designing a drug to prevent hearing damage
- It works by blocking a defective receptor that can lead to the breakdown of auditory synapses
- When the chemical block is placed in the cochleas of mice, hearing is not disturbed but damage is prevented
Hearing loss can be prevented by an injection that scientists call ‘chemical ear protectors’.
Biologists say they have discovered a way to prevent the damage caused by loud sounds without dampening the sound.
Funded by the US Department of Defense, the successful test gives hope that soldiers may one day take a hearing protection device before being exposed to gunshots.
The drug, designed by researchers from the University of Iowa and Washington University in St. Louis, would protect auditory receptors while soldiers can still command and hear each other.
Tinnitus and hearing loss are the main causes of disability for American veterans. A new drug tested in mice can prevent damage to auditory neurons without preventing soldiers from hearing
They discovered a drug that blocks a receptor that prevents the breakdown of vital auditory synapses.
A receptor is part of molecules in ear nerve cells that bridge the pattern of sound and auditory information from sound sensors to the brain.
The successful transfer of sound takes place via a node called a synapse.
The researchers have found that some receptors lack a protein called GluA2, and it is these missing receptors that are responsible for hearing loss.
When biologists blocked the defective receptors in mice, this prevented them from hearing damage.
Professor Steven Green said: “Now we have a medicine that does not prevent hearing, but does damage hearing.”
He added: “It was not just putting on ear protectors – these ear protectors prevent the damage caused by loud sounds but do not dampen the sound.”
‘Permanent hearing damage can be caused by noise levels that are considered’ safe ‘and people need to be careful about exposure to noise because we cannot repair synapses or regenerate hair cells.
“Our chemical ear protectors are currently just an indication of the direction that research can take, not yet a proven, safe means of protection in humans.”
Dr. Mark Rutherford, an expert in head and neck surgery at the University of Washington, said for a long time that this common hearing loss was caused by an influx of calcium.
He added: “Cochlear synapses have long been believed not to be permeable to calcium because all synapses have the GluA2 subunit.
“We have discovered that cochlear synapses have both GluA2-missing and GluA2-containing glutamate receptors, which means that some of them are indeed highly permeable to calcium.
“With high resolution microscopy of cochlear synapses, we have provided a mechanistic explanation for the protection of these synapses against exposure to noise from the calcium-permeable glutamate receptor blocker IEM-1460.”
In this study, published in the Proceedings of the National Academy of Sciences, IEM-1460 was introduced directly into the cochlea of mice via a surgical procedure.
Green hopes to find other drugs that can prevent hearing damage and that can be administered non-invasively.
If their new medicine continues to perform well, this can be life-changing for many people, but especially for soldiers.
A study published in the Journal of General Internal Medicine estimated that between 16.4 and 26.6 percent of male veterans from the wars in Afghanistan and Iraq who visited VAs in the US had severe hearings and / or tinnitus.
Some estimates suggest that as many as 52 percent of combat soldiers have moderate or worse hearing loss.
And this damage has major consequences for veterans.
Tinnitus and hearing loss are the two main reasons that former US soldiers submit disabilities to the Department of Veteran Affairs.