Genetic Hearing Loss Might Be Treatable With A Common Drug

Over the years, we've seen more than our fair share of attempts to reverse hearing loss. While many options are more focused on finding new types of gene therapy solutions to help individuals suffering from congenital hearing loss, others are focused on bringing new therapies to life using existing drugs. That's the case with this latest research, which actually found an unexpected solution to help individuals suffering from congenital hearing: Viagra.

With some studies estimating that over one billion people are at risk of hearing loss from exposure to loud sounds, finding a cure for hearing loss is paramount. Although some are working toward ways to undo damaged hearing, other research, like a new study published by members of the international scientific community in the Journal of Clinical Investigation, is more focused on congenital hearing loss, which is hearing loss present at the time of birth, and finding unique ways to treat it.

According to this new research, scientists believe that a specific mutation found in a gene known as CPD may play a very important role in the manifestation of a rare type of hearing loss that can be passed down from generation to generation. Beyond just finding the gene that might be contributing to this congenital hearing loss, the researchers involved in the study say they may have actually found a therapy that can help mitigate the condition, thus helping to restore hearing in individuals that have lived with out it since birth. This isn't the first time we have seen research taking this kind of direction, but this new method relies heavily on Viagra to do the heavy lifting.

The specific type of hearing loss that the researchers focused on here is known as sensorineural hearing loss, or SNHL. The investigation into SNHL and its connection with CPD began when researchers noticed a specific set of mutations that were shared by three otherwise unrelated families in Turkey. SNHL is typically diagnosed in early childhood and usually leads to "irreversible" hearing impairment. While it can be treated with hearing aids and other solutions, nobody has ever found a way to treat the root cause. At least not until now.

After finding the connection between the three families, the researchers began to look through genetic databases. Here they discovered that others with SNHL had similar mutations. A lot of it comes down to how CPD plays a role in hearing overall. Essentially, CPD is responsible for the production of an important enzyme that generates arginine, an amino acid which helps create a crucial neurotransmitter called nitric oxide. Nitric oxide is crucial because it is what transmits signals through the nervous system in the body.

CPD, especially, is vital because it helps to maintain the level of arginine in the hair cells within the ear. This, in turn, determines how quickly and effectively the hair cells can generate nitric oxide, which helped the researchers understand why CPD mutations had such a massive effect on someone's hearing. So how does a common drug help with this?

Researchers began looking for a way to treat the deficiency caused by the CPD mutations. That meant finding ways to compensate for the lost arginine. They found two main ways to approach the problem. The first was to use arginine supplements to augment the arginine levels in the body naturally. The second option was to take sildenafil — the generic name for Viagra — and use it to treat the deficiency.

The researchers discovered that both options worked well in their own ways. The arginine supplements obviously helped improve arginine levels in the body overall. The sildenafil, though, was also helpful because it helped to stimulate one of the major pathways affected by the loss of nitric oxide. Additionally, the study notes that both options helped to improve the cell survival in the fruit flies that they tested it on, reducing hearing loss behaviors in the flies.

Now, it is important to note that this isn't the first time we've seen Viagra used for something other than it's marketed role. In fact, scientists previously said Viagra could be used to treat cancer. The researchers say that by looking at existing drugs like they did here, they can come up with new ways to use products that have already undergone FDA approval, which could hopefully speed up how soon these therapies are available to human patients suffering from these rare conditions. For now, the researchers plan to conduct deeper research into the matter so they can better understand the pathways that rely on nitric oxide, as well as the role that the sensory system of the inner ear plays in congenital hearing loss.