However, a new study published in the Proceedings of the National Academy of Sciences, claim a new drug compound may have the ability to block damaging high volume sounds.
The study explains that researchers have found a drug compound that may prevent noise-induced hearing loss.
Researchers who conducted the study say the data suggests a means of maintaining normal hearing thresholds while protecting against noise-induced synaptopathy, via “selective blockade of CP-AMPARs.”
More than 460 million people in the world are affected by sensorineural hearing loss. The figure is only set to rise, and is estimated by the World Health Organization to hit a high of 900 million by the year 2050.
The cochlea of the inner ear has the important job of detecting the sounds we hear. The inner hair cells which line the cochlea transform the vibrations of sound waves, turning them into chemical signals. In turn, these chemicals and in particular, glutamate, are released from the hair cells. They’re sent to glutamate receptors which are located on the auditory nerve fibers. These then send electrical impulses to the brain. There, they are altered and changed into the audio signals we are familiar with such as music and speech.
A juncture between a hair cell and a nerve fiber is known as a synapse. Too loud a sound can cause a release of more glutamate than is necessary. This can lead to loss of synapses, resulting in sensorineural hearing loss.
“Glutamate receptors are essential for hearing, but overstimulating them can lead to irreversible damage to synapses,” said Mark A. Rutherford, PhD, in the the study’s findings. “What we have found is that glutamate receptors are not all the same, allowing us to block some while leaving others unblocked. When we blocked one subclass of glutamate receptor while leaving the other active, we prevented the damage while maintaining hearing function.”
Blocking all of the receptors could preserve hearing in theory. However, it would also simulate temporary deafness. This would not really help anyone. There are in fact two different kinds of receptors, ones which allow calcium through and the others which block calcium.
As a rule both types of receptors are triggered with loud noises. But with an application of the new drug compound IEM-1460, more calcium than would normally be the case is allowed through. In doing so, hearing loss is prevented. The receptors not being blocked still allow normal sound through, so the hearing is not even temporally impaired.
“Even moderate noise can cause damage to these synapses, and the damage accumulates as we age,” said senior author Steven H. Green PhD, at the University of Iowa. “With our aging population, the number of people living with disabling hearing loss is increasing rapidly. This is the motivation behind our labs’ collaboration: We are seeking preventive therapies that can protect this vital sensory function in the setting of damaging noise levels while still letting people hear as they normally would.”
“We are seeking preventive therapies that can protect this vital sensory function in the setting of damaging noise levels”
At this time, the drug compound IEM-1460 has yet to be tested on humans. It has only been successful on rodents and primates so far. The implications could be huge, according to the researchers. A major one is that of military personnel going into combat. The ability to be able to prevent such a debilitating disability would be an amazing breakthrough.
The test results so far are very promising. They could lead to a much better chance of sensorineural hearing loss prevention in the future.