Yale researchers find environmental toxins disruptive to hearing in mammals

April 11, 2006

New Haven, Conn.--Yale School of Medicine researchers have new data showing chloride ions are critical to hearing in mammals, which builds on previous research showing a chemical used to keep barnacles off boats might disrupt the balance of these ions in ear cells.

"Our data are the first to directly show that chloride ions are crucial for our exquisite sense of hearing," said Joseph Santos-Sacchi, professor in the Departments of Surgery and Neurobiology and first author of the study in the Journal of Neuroscience. "These data also indicate that the hearing in marine and other mammals could be affected by environmental toxins, such as TBT (tributyl tin), because they appear to alter the balance of chloride ions in the outer hair cell."

Sensitive hearing in mammals relies on cochlear amplification resulting from the motor activity of outer hair cells. They are the only group of animals that have outer hair cells. Additionally, TBT is known to damage the immune and hormonal systems of marine mammals.

In this study on guinea pigs, Santos-Sacchi tested whether TBT or salicylate, which is a chemical that occurs naturally in plants and is a component of aspirin, interfered with the guinea pigs' ability to hear. He found that TBT, salicylate, or otherwise altering the extracellular chloride levels in the cochleas, interfered with the balance of chloride in the outer hair cells and caused profound changes in sound amplification in the inner ear.

In his previous study using TBT on isolated cells only, Santos-Sacchi had proposed that the ear's ability to perceive sound would be compromised. He also speculated that whales and other marine mammals exposed to TBT would have altered sound localization abilities. The present findings confirm that their hearing is altered in mammals.

"Since many marine mammals use echolocation or sonar to get around, this could be contributing to whales and dolphins beaching and hitting ships," Santos-Sacchi said.
-end-
Co-authors include Lei Song, M.D., Jiefu Zheng, M.D., and Alfred Nuttall. The study was funded in part by the National Institutes of Health and the National Institute on Deafness and Other Communication Disorders.

Journal of Neuroscience: (published online April 12, 2006 DOI 10.1523/JNEUROSCI.4548-05.2006)

Yale University

Related Hearing Articles from Brightsurf:

Two molecular handshakes for hearing
Scientists have mapped and simulated those filaments at the atomic level, a discovery that shed lights on how the inner ear works and that could help researchers learn more about how and why people lose the ability to hear.

Proof-of-concept for a new ultra-low-cost hearing aid for age-related hearing loss
A new ultra-affordable and accessible hearing aid made from open-source electronics could soon be available worldwide, according to a study published September 23, 2020 in the open-access journal PLOS ONE by Soham Sinha from the Georgia Institute of Technology, Georgia, US, and colleagues.

Ultra-low-cost hearing aid could address age-related hearing loss worldwide
Using a device that could be built with a dollar's worth of open-source parts and a 3D-printed case, researchers want to help the hundreds of millions of older people worldwide who can't afford existing hearing aids to address their age-related hearing loss.

A promise to restore hearing
For the first time, researchers have used base editing to restore partial hearing to mice with a recessive mutation in the gene TMC1 that causes complete deafness, the first successful example of genome editing to fix a recessive disease-causing mutation.

Surprising hearing talents in cormorants
The great cormorant has more sensitive hearing under water than in air.

Veterinarians: Dogs, too, can experience hearing loss
Just like humans, dogs are sometimes born with impaired hearing or experience hearing loss as a result of disease, inflammation, aging or exposure to noise.

Older people who use hearing aids still report hearing challenges
A high proportion of older people with hearing aids, especially those with lower incomes, report having trouble hearing and difficulty accessing hearing care services, according to a study from researchers at Johns Hopkins Bloomberg School of Public Health.

Hearing class
New study finds that the class of neurons responsible for transmitting information from the inner ear to the brain is composed of three molecularly distinct subtypes.

Hearing tests on wild whales
Scientists published the first hearing tests on a wild population of healthy marine mammals.

Genes critical for hearing identified
Fifty-two previously unidentified genes that are critical for hearing have been found by testing over 3,000 mouse genes.

Read More: Hearing News and Hearing Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.